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Harvesting as a potential selective pressure on behavioural traits

Journal of Applied Ecology

February 2017
54(6)

DOI:10.1111/1365-2664.12893

Authors:

Martin Leclerc

Université du Québec à Chicoutimi

Andreas Zedrosser

University of South-Eastern Norway

Fanie Pelletier

Université de Sherbrooke

Human activities are a major evolutionary force affecting wild populations. Selective pressure from harvest has mainly been documented for life‐history and morphological traits. The probability for an individual to be harvested, however, may also depend on its behaviour. We report empirical studies that examined whether harvesting can exert selective pressures on behavioural traits. We show that harvest‐induced selection on behavioural traits is not specific to a particular harvest method and can occur throughout the animal kingdom. Synthesis and applications . Managers need to recognize that artificial selection caused by harvesting is possible. More empirical studies integrating physiological, behavioural, and life‐history traits should be carried out to test specific predictions of the potential for harvest‐induced selection on heritable traits using models developed in fisheries. To limit selective pressure on behaviour imposed by harvesting, managers could reduce harvest quotas or vary harvest regulations over time and/or space to reduce the strength of selection on a particular phenotype.

. Examples of experimental and observational studies showing that harvest can act as a selective pressure on behaviour

…

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COMMENTARY

Harvesting as a potential selective pressure on

behavioural traits

Martin Leclerc*

, Andreas Zedrosser

2,3

and Fanie Pelletier

Canada Research Chair in Evolutionary Demography and Conservation & Centre for Northern Studies, D 

epartement

de biologie, Universit

e de Sherbrooke, Sherbrooke, QC J1K2R1, Canada;

Faculty of Technology, Natural Sciences

and Maritime Sciences, Department of Natural Sciences and Environmental Health, University College of Southeast

Norway, N-3800 Bø i Telemark, Norway; and

Department of Integrative Biology, Institute of Wildlife Biology and

Game Management, University of Natural Resources and Applied Life Sciences, Vienna, Gregor Mendel Str. 33,

A–1180 Vienna, Austria

Summary

1. Human activities are a major evolutionary force affecting wild populations. Selective pres-

sure from harvest has mainly been documented for life-history and morphological traits. The

probability for an individual to be harvested, however, may also depend on its behaviour.

2. We report empirical studies that examined whether harvesting can exert selective pressures

on behavioural traits.

3. We show that harvest-induced selection on behavioural traits is not speciﬁc to a particular

harvest method and can occur throughout the animal kingdom.

4. Synthesis and applications. Managers need to recognize that artiﬁcial selection caused by

harvesting is possible. More empirical studies integrating physiological, behavioural, and life-

history traits should be carried out to test speciﬁc predictions of the potential for harvest-

induced selection on heritable traits using models developed in ﬁsheries. To limit selective

pressure on behaviour imposed by harvesting, managers could reduce harvest quotas or vary

harvest regulations over time and/or space to reduce the strength of selection on a particular

phenotype.

Key-words: angling, evolutionary consequences, exploitation, ﬁsheries, gillnet, harvest-

induced selection, hunting, passive and active gear, vulnerability

Introduction

Humans are considered as one of the major selective forces

shaping traits of species (Palumbi 2001) and may cause faster

phenotypic changes than many natural drivers (Hendry,

Farrugia & Kinnison 2008; Darimont et al. 2009). Pheno-

typic changes are particularly drastic when humans act as

predators and harvest wild populations (Darimont et al.

2009). Harvesting can induce selective pressures on wild ani-

mal populations by increasing mortality and by non-random

removal of speciﬁc phenotypes. Harvesting has been shown

to induce selective pressure in several species (Allendorf

et al. 2008) that may ultimately result in evolutionary

responses (Jørgensen et al. 2007; Pigeon et al. 2016).

Selective pressure caused by human harvest, hereafter

referred to as harvest-induced selection, has mostly been

documented for life-history and morphological traits and

can be caused by size-selective harvesting. For example,

trophy hunting of male bighorn sheep (Ovis canadensis)

selected for smaller horn size (Coltman et al. 2003; Pigeon

et al. 2016), and size-selective ﬁshing affected the evolu-

tion of life histories in zebra ﬁsh (Danio rerio) (Uusi-

Heikkil€

aet al. 2015). In size-selective harvesting, typically

a speciﬁc phenotype is targeted leading to harvest-induced

selection. Harvest-induced selection on behavioural traits,

however, can be due to behavioural differences between

individuals affecting their probability of being harvested

(Heino & Godø 2002; Uusi-Heikkil€

aet al. 2008). This

pattern was observed in behavioural studies showing that

the probability of capturing or sampling (for scientiﬁc

research instead of harvesting) a speciﬁc individual in a

population could be biased due to consistent individual

differences in behaviour, i.e. animal personality (Biro &

Dingemanse 2009; Carter et al. 2012; Biro 2013). These

individual behavioural differences are often heritable

(Postma 2014; Dochtermann, Schwab & Sih 2015).

*Correspondence author. E-mail: martin.leclerc2@usherbrooke.ca

Journal of Applied Ecology 2017, 54, 1941–1945 doi: 10.1111/1365-2664.12893

Humans can therefore, consciously or not, modulate the

evolution of animal behaviour by removing (harvesting)

or reproducing (breeding) speciﬁc individuals within a

population (Price 1984). Although important for wildlife

management and conservation, much less attention has

been devoted to harvest-induced selection on behavioural

traits compared to life-history or morphological traits

(Uusi-Heikkil€

aet al. 2008; Heino, D

ıaz Pauli & Dieck-

mann 2015) and to whether this selection may lead to

evolution of behaviours that are different from those

favoured by natural selection (e.g. Olsen & Moland 2011

for morphological traits).

Harvesting as a selective pressure on

behavioural traits

Most of the theoretical work and predictions for beha-

vioural harvest-induced selection are derived from the

ﬁsheries literature. Arlinghaus et al. (2016) suggested that

harvest should select for shyer and more vigilant individ-

uals. In ﬁsheries, predictions made on harvest-induced

selection often depend on the gear type used, and Al

os,

Palmer & Arlinghaus (2012) predicted that passive gear

should select for individuals with lower activity levels. In

sport hunting, a hunter must see an individual of the

species of interest before she/he can select a target ani-

mal based on a morphological trait or a sex/age class.

Therefore, we hypothesize that behavioural traits that

increase vulnerability or visibility, such as selection of

open areas, more active individuals during hunting

hours, or boldness, should have a strong effect on the

probability that an individual will present itself as a pos-

sible target.

Here, we report studies where harvest-induced selection

of behavioural traits was clearly investigated. We searched

the scientiﬁc literature database Scopus

for peer-

reviewed papers using different combinations of the fol-

lowing seven keywords: harvesting, hunting, ﬁsheries,

behaviour, vulnerability, exploitation and selective pres-

sure. The literature contains numerous studies on the

immediate effects of harvesting on behaviour (i.e. plastic

response or ‘learning’) (e.g. Raat 1985; Ordiz et al. 2012)

or studies showing behavioural differences between high

and low vulnerability ﬁsh strains (e.g. Nannini et al. 2011;

Sutter et al. 2012), or studies showing behavioural differ-

ences between ﬁsh caught with different methods or lures

(e.g. Wilson et al. 2015), which suggests that harvesting

might induce a selective pressure on behaviours. Here,

however, we only retained studies that directly examined

whether harvesting acted as a selective pressure on beha-

vioural traits. The limited amount of literature examining

harvest-induced selection on behaviour likely reﬂects the

difﬁculties in collecting quantitative information on beha-

vioural traits expressed by harvested and non-harvested

individuals necessary to investigate behavioural harvest-

induced selection. This is particularly true for ﬁsh,

because it is rarely possible to make observations on ﬁsh

that are not captured (H€

ark€

onen et al. 2016, but see

Olsen et al. 2012), and longitudinal behavioural time-ser-

ies data from wild populations hardly exist (Jørgensen &

Holt 2013). We categorized the 13 retained studies in two

groups: experimental studies in the laboratory or natural

conditions, and observational studies in the wild.

Experimental studies

We found seven experimental studies showing that harvest

can act as a selective pressure on behavioural traits

(Table 1; but see Vainikka, Tammela & Hyv€

arinen 2016).

From the seven studies showing harvest-induced selection

of behavioural traits, six were conducted in ﬁshes and one

in a crustacean. Individuals showed different vulnerability

to angling in largemouth bass (Micropterus salmoides)

(Philipp et al. 2009) and common carp (Cyprinus carpio)

(Klefoth, Pieterek & Arlinghaus 2013), and traps removed

bolder guppies (Poecilia reticulata) and common yabby

(Cherax destructor) (Biro & Sampson 2015; Diaz Pauli

et al. 2015). Trawling removed shyer guppies (Diaz Pauli

et al. 2015) and minnows (Phoxinus phoxinus) with lower

swim speed (Killen, Nati & Suski 2015). These studies

suggest that harvesting can act as a selective pressure on a

behavioural trait and that passive gear should select

against boldness and more explorative individuals, while

active gear should select against shyness, and angling

selects against more aggressive, bold and vulnerable indi-

viduals (Heino & Godø 2002; Arlinghaus et al. 2016).

Harvest-induced selection patterns obtained in laboratory

experiments appear to be consistent with those observed

in experiments conducted in natural settings (Biro & Post

2008), suggesting that harvesting can act as a selective

pressure in the wild.

Observational studies

We found six studies showing harvest-induced selection

on different behavioural traits in the wild, ranging from

the timing of migration to boldness and defensiveness

(Table 1). These studies involved ﬁshes, snakes, birds and

mammals in Japan, Norway, United Kingdom, Canada

and the USA. Similar to experimental studies, observa-

tional studies showed that harvest-induced selection was

caused by different harvest methods (shotgun, riﬂe hunt-

ing, passive gear, angling), and that behavioural traits

under selection may vary in relation to the harvest

method used (Table 1). In sockeye salmon (Oncorhynchus

nerka) harvesting selected against individuals that

migrated later in the season in a population where

exploitation rates vary systematically over the course of

the ﬁshing season (Quinn et al. 2007). In this population,

migration timing became earlier over the years (Quinn

et al. 2007). Such temporal behavioural changes could be

caused by environmental factors, but could also be, at

least partly, a response to harvest-induced selection if

migration timing is heritable (Quinn et al. 2007).

1942 M. Leclerc, A. Zedrosser & F. Pelletier

Consequences of behavioural harvest-induced

selection

Behavioural traits under harvest-induced selection can

only evolve if they are heritable (Postma 2014; Dochter-

mann, Schwab & Sih 2015). In addition to the changes in

migration timing of sockeye salmon discussed above

(Quinn et al. 2007), two studies suggested that harvest

might have been important in the evolution of a genetic

locus related to habitat use of Atlantic cod (Gadus mor-

hua) in Iceland (



Arnason, Hernandez & Kristinsson 2009;

Jakobsdottir et al. 2011). However, we found no observa-

tional studies that could unequivocally show evolution in

behaviour caused by harvesting. Absence of evidence for

harvest-induced evolution of behavioural traits in the

wild, however, does not imply that such evolution is unli-

kely or uncommon. Instead, it may reﬂect the difﬁculties

to obtain the necessary longitudinal data on behaviours in

harvested populations (Clutton-Brock & Sheldon 2010;

Jørgensen & Holt 2013). Even when adequate data are

available, it remains challenging to show that harvest is

the driver of evolutionary change and to disentangle phe-

notypic plasticity from genetic change (Meril€

a & Hendry

2014). Although they have not been documented in the

wild, evolutionary changes in behavioural traits due to

harvest have been shown in experimental studies (Philipp

et al. 2009). Laboratory experiments are useful to evaluate

the potential for harvest-induced selection and

evolutionary response in behavioural traits, but extrapola-

tion of results to natural systems is difﬁcult, as some rela-

tionships observed in the laboratory might not persist in

the wild (Wilson et al. 2011).

Conclusions

Humans have harvested wild animals for millennia and

human evolution is strongly linked with harvesting. How-

ever, technological developments have increased our efﬁ-

ciency to harvest, with many consequences (Milner,

Nilsen & Andreassen 2007; Allendorf et al. 2008; Fenberg

& Roy 2008). Morphological, life-history and behavioural

traits form the phenotype of an individual and thus affect

its vulnerability to harvest (Uusi-Heikkil€

aet al. 2008).

There is increasing evidence that behavioural traits are

correlated with physiological and life-history traits (Biro

& Stamps 2008; R

eale et al. 2010). Therefore, even if har-

vesting speciﬁcally targets a behavioural trait, changes in

life-history, morphological, and/or physiological traits can

be observed. For example, changes in behaviours were

observed due to size-selective harvesting in zebra ﬁsh

(Uusi-Heikkil€

aet al. 2015), and size-selective harvesting

of Atlantic silverside (Menidia menidia) resulted in lower

larval growth rate, food consumption rate and conversion

efﬁciency, and vertebrae number (Walsh et al. 2006;

Duffy et al. 2013). If individuals with certain life-history,

morphological and behavioural phenotypes are heavily

Table 1. Examples of experimental and observational studies showing that harvest can act as a selective pressure on behaviour

Species Harvest method Trait

Direction of the selective effect

ReferenceHarvest selects against individual that are:

Experimental studies in the laboratory or in natural conditions

Poecilia reticulata Trap Bold–Shy Bolder Diaz Pauli et al. (2015)

Trawl Bold–Shy Shyer Diaz Pauli et al. (2015)

Phoxinus phoxinus Trawl Swim speed Slower Killen, Nati & Suski

(2015)

Salmo trutta Fly-ﬁshing Exploration More explorative H€

ark€

onen et al. (2014)

Cyprinus carpio Angling Vulnerability More vulnerable Klefoth, Pieterek &

Arlinghaus (2013)

Micropterus salmoides Angling Vulnerability More vulnerable Philipp et al. (2009)

Oncorhynchus mykiss Gillnet Bold/Shy–Fast/Slow Faster-bolder Biro & Post (2008)

Cherax destructor Trap Bold–Shy Bolder Biro & Sampson (2015)

Observational studies

Oncorhynchus nerka Angling Migration timing Migrated later in season Quinn et al. (2007)

Gadus morhua Passive gear Habitat use Use more shallow water Olsen et al. (2012)

Passive gear Vertical migration Have a strong diel vertical migration Olsen et al. (2012)

Passive gear Horizontal movement Have a predictable movement pattern Olsen et al. (2012)

Gloydius blomhofﬁi Not mentioned Flight distance Have lower ﬂight distance Sasaki, Fox & Duvall

(2009)

Not mentioned Defensiveness More defensive Sasaki, Fox & Duvall

(2009)

Phasianus colchicus Shotgun hunting Bold–Shy Bolder Madden & Whiteside

(2014)

Cervus elaphus Riﬂe hunting Habitat use Use habitat with less concealing cover Lone et al. (2015)

Riﬂe hunting Habitat use Use open areas Ciuti et al. (2012)

Riﬂe hunting Habitat use Closer to roads and use ﬂatter terrain Ciuti et al. (2012)

Riﬂe hunting Movement rate Have higher movement rate Ciuti et al. (2012)

Behavioural harvest-induced selection 1943

harvested, selection may quickly lead to the evolution of a

population with a lower harvest yield (Conover & Munch

2002), because this population will now mostly be com-

posed of individuals with lower growth rate (Conover &

Munch 2002; Biro & Sampson 2015) that are also more

difﬁcult to harvest (Philipp et al. 2009). In many cases,

selective pressures imposed by harvesting oppose natural

selection (Conover 2007; Olsen & Moland 2011). While

some traits can genetically recover after harvest-induced

selection ceases (Conover, Munch & Arnott 2009), some

traits may not (Salinas et al. 2012; Pigeon et al. 2016),

which can impair population recovery after harvest has

ceased (Laugen et al. 2014).

Recommendations

Even though behaviours are often easier to observe and

quantify in terrestrial ecosystems, most of the literature

and predictions on behavioural harvest-induced selection

come from ﬁsheries. Despite differences in the harvest

methods used in ﬁsheries and hunting, behavioural data

from terrestrial harvested populations can be complemen-

tary to ﬁsheries data and could offer an opportunity to

test predictions developed for ﬁsheries in terrestrial

ecosystems. For example, predictions made for passive

gear in ﬁsheries could be applied to ‘still hunting’ or ‘bait

hunting’, but might not be appropriate for ‘stalking’.

Therefore, we suggest a synergistic approach and recom-

mend to increase discussions and collaborations between

researchers studying harvest-induced selection in ﬁsheries

and terrestrial ecosystems.

Integrating genetic and evolutionary effects of harvest-

ing into management and conservation is central for

achieving sustainable harvesting (Conover & Munch 2002;

Allendorf et al. 2008). Acknowledging that harvest is

selective by nature is the ﬁrst step towards that goal. Even

if harvest is random regarding phenotypes, it increases

mortality and therefore selects for faster growing and ear-

lier reproducing individuals (rlife-history strategy) rather

than slow growing and late reproducing individuals (K

life-history strategy) (Pianka 1970). Ideally, in harvested

populations, monitoring programs should be introduced

to detect and monitor potential harvest-induced selection

and its consequences. Such programs would require longi-

tudinal data on multiple phenotypic traits, including

behavioural traits, of harvested and non-harvested indi-

viduals in the population. This would allow evaluating the

direction and strength of harvest-induced selection in

comparison to natural selection. When required, different

mitigation measures could be implemented in manage-

ment plans to reduce the impacts of harvest-induced

selection. For example, reducing harvest quotas should

reduce the strength of selection or managers could estab-

lish harvest regimes that mimic natural selection (Milner,

Nilsen & Andreassen 2007).

Such monitoring programs are challenging tasks requir-

ing a considerable amount of time and money. In the

meantime, we suggest using a precautionary approach

when harvesting natural populations. Harvest quotas

should not be based on maximum yield but rather aim at

preserving natural variation shaped by natural selection

(Fenberg & Roy 2008). We suggest, based on our results,

to vary harvest regulations (e.g. based on sex, age or

phenotypes harvested and harvest methods used) spatio-

temporally to reduce the strength of selection on a

particular phenotype.

Authors’ contributions

All authors conceived the idea; M.L. conducted the literature search and

the ﬁrst draft of the manuscript. All authors contributed critically to the

drafts and gave ﬁnal approval for publication.

Acknowledgements

We thank M. Festa-Bianchet and two anonymous reviewers for com-

ments on an earlier version of this manuscript. M.L. was supported

ﬁnancially by NSERC and FRQNT. F.P. was funded by NSERC

discovery grant and by the Canada Research Chair in Evolutionary

Demography and Conservation. A.Z. acknowledges funding from the

Polish-Norwegian Research Program operated by the National Center

for Research and Development under the Norwegian Financial Mecha-

nism 2009-2014 in the frame of project contract no. POL-NOR/198352/

85/2013. This is paper no. 229 of the Scandinavian Brown Bear Research

Project.

Data accessibility

Data have not been archived because this article does not contain data.

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e Villard

Behavioural harvest-induced selection 1945

The role of human hunters and natural predators in shaping the selection of behavioural types in male wild turkeys

Article

Full-text available

Nov 2024

The expression of behaviour can vary both among (i.e. behavioural types (BTs)) and within individuals (i.e. plasticity), and investigating causes and consequences of variation has garnered significant attention. Conversely, studies quantifying harvest-induced selection (HIS) on behavioural traits have received significantly less attention, and work investigating HIS and natural selection simultaneously is rare. We studied sources of variation in three movement traits that represented risk-taking and one trait that represented exploration in male eastern wild turkeys (Meleagris gallopavo silvestris). We used data from 109 males in two hunted populations located in Georgia and South Carolina, USA. We assessed how both hunters and natural predators simultaneously influenced the selection of male turkey BTs. We found significant among-individual variation in all movement traits and adjustments in risk-taking and exploration relative to whether hunting was occurring. We observed that predators selected against similar BTs across both populations, whereas hunters selected for different BTs across populations. We also demonstrated that significant HIS acts on risk-taking behaviours in both populations, which could render wild turkeys more difficult to harvest if these traits are indeed heritable.

Individual behaviour, growth, survival and vulnerability to hunting in a large mammal

Article

Full-text available

Feb 2024

Humans have exploited wild animals for thousands of years. Recent studies indicate that harvest‐induced selection on life‐history and morphological traits may lead to ecological and evolutionary changes. Less attention has been given to harvest‐induced selection on behavioural traits, especially in terrestrial systems. We assessed in a wild population of large terrestrial mammals whether decades of hunting led to harvest‐induced selection on trappability, a proxy of risk‐taking behaviour. We investigated links between trappability, horn growth and survival across individuals in early life and quantified the correlations between early‐life trappability and horn growth with availability to hunters and probability of being shot. We found positive among‐individual correlations between early‐life trappability and horn growth, early‐life trappability and survival and early‐life horn growth and survival. Faster growing individuals were more likely to be available to hunters and shot at a young age. We found no correlations between early‐life trappability and availability to hunters or probability of being shot. Our results show that correlations between behaviour and growth can occur in wild terrestrial population but may be context dependent. This result highlights the difficulty in formulating general predictions about harvest‐induced selection on behaviour, which can be affected by species ecology, harvesting regulations and harvesting methods used. Future studies should investigate mechanisms linking physiological, behavioural and morphological traits and how this effects harvest vulnerability to evaluate the potential for harvest to drive selection on behaviour in wild animal populations.

Personality dimensions in the common octopus (Octopus vulgaris)

Article

Nov 2024
BEHAVIOUR

Understanding the origin, universality, and maintenance of among-individual variation in behaviour is a current focus of behavioural ecology and comparative psychology. Research on animal personality emphasising the central role of the individual contributes to conservation efforts and animal welfare by tailoring guidelines and interventions at the individual level. Cephalopods are under-studied in this respect, despite being the only invertebrate group currently included in international directives for the protection of animals used for scientific purposes. Here, we assessed among-individual variation in behavioural responses (i.e., animal personality) of 21 common octopuses (Octopus vulgaris) temporarily kept in captivity. We performed a battery of tests across three different experimental contexts, namely a Startle test, a Foraging test, and a Disturbance test, each repeated for four consecutive days, adapting established protocols from other cephalopods. Behavioural variables were moderately repeatable. Results of a principal component analysis revealed a three-component structure, with components we labelled Alertness, Exploration, and Boldness. The components were also moderately repeatable. The components Exploration and Boldness predicted each other across experimental contexts, suggesting a behavioural syndrome. Overall, findings indicate marked individual differences in common octopuses, and provide evidence of personality dimensions in a widely used animal model in neurophysiology and cognition. Our findings thus contribute to the study of the evolution of personality structure from a comparative perspective, and may help individual-level welfare refinement. Published with license by Koninklijke Brill BV |

Migration patterns, habitat use and genetic origins of sea trout (Salmo trutta) in Norfolk chalk streams: implications for management of a mixed stock fishery

Article

Full-text available

Nov 2024

Sea trout, the anadromous ecotype of the species Salmo trutta , are subject to multiple threats, including exploitation and aquaculture impacts in the marine environment, habitat fragmentation and pollution in freshwaters, loss of genetic resilience due to interbreeding with hatchery strains and environmental change. Small streams contribute relatively little biomass to European sea trout stocks but are thought to be important in maintaining genetic diversity and therefore wider population resilience. The current study combined data from acoustic telemetry, stable isotopes, genetics and scalimetry to assess the current status of sea trout in the rivers Stiffkey and Glaven, two locally important chalkstreams in East Anglia, UK, to provide an evidence base for future management. The incidence of anadromy was low, and most sea trout were near migrants, residing in the lower reaches of rivers and close to the tidal outfalls. A small number migrated to the North Sea where they were vulnerable to exploitation in the coastal fishery, which comprises a mixed stock. Straying between the two rivers was recorded among 10% of sea trout, leading to apparent high gene flow. Nonetheless, genetic data also demonstrated structuring of River Glaven trout into two distinct groups. Quantification of patterns of freshwater and estuarine habitat use, and of passage at cross-channel obstructions, was used to identify where remedial measures such as habitat restoration would be most effectively targeted. Findings are discussed in the context of local supplementary stocking and the potential impact of the nearshore fishery on limited and vulnerable small stream anadromous trout populations.

Demographic patterns of walleye (Sander vitreus) reproductive success in a Wisconsin population

Article

Full-text available

Mar 2024
EVOL APPL

Harvest in walleye Sander vitreus fisheries is size‐selective and could influence phenotypic traits of spawners; however, contributions of individual spawners to recruitment are unknown. We used parentage analyses using single nucleotide polymorphisms to test whether parental traits were related to the probability of offspring survival in Escanaba Lake, Wisconsin. From 2017 to 2020, 1339 adults and 1138 juveniles were genotyped and 66% of the offspring were assigned to at least one parent. Logistic regression indicated the probability of reproductive success (survival of age‐0 to first fall) was positively (but weakly) related to total length and growth rate in females, but not age. No traits analyzed were related to reproductive success for males. Our analysis identified the model with the predictors' growth rate and year for females and the models with year and age and year for males as the most likely models to explain variation in reproductive success. Our findings indicate that interannual variation (i.e., environmental conditions) likely plays a key role in determining the probability of reproductive success in this population and provide limited support that female age, length, and growth rate influence recruitment.

Demographic and evolutionary consequences of hunting of wild birds

Article

Full-text available

Feb 2024
BIOL REV

Hunting has a long tradition in human evolutionary history and remains a common leisure activity or an important source of food. Herein, we first briefly review the literature on the demographic consequences of hunting and associated analytical methods. We then address the question of potential selective hunting and its possible genetic/evolutionary consequences. Birds have historically been popular models for demographic studies, and the huge amount of census and ringing data accumulated over the last century has paved the way for research about the demographic effects of harvesting. By contrast, the literature on the evolutionary consequences of harvesting is dominated by studies on mammals (especially ungulates) and fish. In these taxa, individuals selected for harvest often have particular traits such as large body size or extravagant secondary sexual characters (e.g. antlers, horns, etc.). Our review shows that targeting individuals according to such genetically heritable traits can exert strong selective pressures and alter the evolutionary trajectory of populations for these or correlated traits. Studies focusing on the evolutionary consequences of hunting in birds are extremely rare, likely because birds within populations appear much more similar, and do not display individual differences to the same extent as many mammals and fishes. Nevertheless, even without conscious choice by hunters, there remains the potential for selection through hunting in birds, for example by genetically inherited traits such as personality or pace‐of‐life. We emphasise that because so many bird species experience high hunting pressure, the possible selective effect of harvest in birds and its evolutionary consequences deserves far more attention, and that hunting may be one major driver of bird evolutionary trajectories that should be carefully considered in wildlife management schemes.

Freshwater fish personalities in the Anthropocene

Article

Full-text available

Feb 2024

Fiddler crabs from highly disturbed beaches are more sensitive to human presence

Article

Full-text available

Jun 2024
AN ACAD BRAS CIENC

The presence of humans frequently modifies the behavior of animals, particularly their foraging patterns, compromising energetic demands. The fiddler crab Leptuca leptodactyla inhabits mangroves with high degrees of anthropogenic influence. Thus, we tested if populations living in highly anthropized mangroves respond differently from those living in more protected areas. We predict that individuals from touristy areas will be more tolerant to humans and will resume their activities sooner after disturbance. To do so, we conducted an experiment that consisted in the approach of an observer to the burrows, recording the response of individuals to the stimuli. The experiment took place in July 2022, in Ubatuba, São Paulo, Brazil. We analysed the duration and latency of various behaviors of a total of 80 adult males from two populations (high and low anthropogenic influence). Contrary to our predictions, individuals from the anthropized population were less tolerant, spending more time inside their burrows and taking longer to resume their activities. Therefore, fiddler crabs were not habituated to human presence. These results help us understand the learning process in invertebrates and their ability to select stimuli, contributing to understanding the impacts of human-wildlife interactions.

Behavioural responses of brown bears to roads and hunting disturbance

Article

Full-text available

Jun 2024

Harvest regulations commonly attenuate the consequences of hunting on specific segments of a population. However, regulations may not protect individuals from non‐lethal effects of hunting and their consequences remain poorly understood. In this study, we compared the movement rates of Scandinavian brown bears (Ursus arctos, n = 47) across spatiotemporal variations in risk in relation to the onset of bear hunting. We tested two alternative hypotheses based on whether behavioural responses to hunting involve hiding or escaping. If bears try to reduce risk exposure by avoiding being detected by hunters, we expect individuals from all demographic groups to reduce their movement rate during the hunting season. On the other hand, if bears avoid hunters by escaping, we expect them to increase their movement rate in order to leave high‐risk areas faster. We found an increased movement rate in females accompanied by dependent offspring during the morning hours of the bear hunting season, a general decrease in movement rate in adult lone females, and no changes in males and subadult females. The increased movement rate that we observed in females with dependant offspring during the hunting season was likely an antipredator response because it only occurred in areas located closer to roads, whereas the decreased movement rate in lone females could be either part of seasonal activity patterns or be associated with an increased selection for better concealment. Our study suggests that female brown bears accompanied by offspring likely move faster in high‐risk areas to minimize risk exposure as well as the costly trade‐offs (i.e. time spent foraging vs. time spent hiding) typically associated with anti‐predator tactics that involve changes in resource selection. Our study also highlights the importance of modelling fine‐scale spatiotemporal variations in risk to adequately capture the complexity in behavioural responses caused by human activities in wildlife.

The impact of boldness on demographic rates and life‐history outcomes in the wandering albatross

Article

Full-text available

Mar 2024
J ANIM ECOL

Differences among individuals within a population are ubiquitous. Those differences are known to affect the entire life cycle with important consequences for all demographic rates and outcomes. One source of among‐individual phenotypic variation that has received little attention from a demographic perspective is animal personality, which is defined as consistent and heritable behavioural differences between individuals. While many studies have shown that individual variation in individual personality can generate individual differences in survival and reproductive rates, the impact of personality on all demographic rates and outcomes remains to be assessed empirically. Here, we used a unique, long‐term, dataset coupling demography and personality of wandering albatross (Diomedea exulans) in the Crozet Archipelago and a comprehensive analysis based on a suite of approaches (capture‐mark‐recapture statistical models, Markov chains models and structured matrix population models). We assessed the effect of boldness on annual demographic rates (survival, breeding probability, breeding success), life‐history outcomes (life expectancy, lifetime reproductive outcome, occupancy times), and an integrative demographic outcome (population growth rate). We found that boldness had little impact on female demographic rates, but was very likely associated with lower breeding probabilities in males. By integrating the effects of boldness over the entire life cycle, we found that bolder males had slightly lower lifetime reproductive success compared to shyer males. Indeed, bolder males spent a greater proportion of their lifetime as non‐breeders, which suggests longer inter‐breeding intervals due to higher reproductive allocation. Our results reveal that the link between boldness and demography is more complex than anticipated by the pace‐of‐life literature and highlight the importance of considering the entire life cycle with a comprehensive approach when assessing the role of personality on individual performance and demography.

Does boldness explain vulnerability to angling in Eurasian perch Perca fluviatilis ?

Article

Full-text available

Mar 2016

Consistent individual differences (CIDs) in behavior are of interest to both basic and applied research, because any selection acting on them could induce evolution of animal behavior. It has been suggested that CIDs in the behavior of fish might explain individual differences in vulnerability to fishing. If so, fishing could impose selection on fish behavior. In this study, we assessed boldness-indicating behaviors of Eurasian perch Perca fluviatilis using individually conducted experiments measuring the time taken to explore a novel arena containing predator (burbot, Lota lota) cues. We studied if individual differences in boldness would explain vulnerability of individually tagged perch to experimental angling in outdoor ponds, or if fishing would impose selection on boldness-indicating behavior. Perch expressed repeatable individual differences in boldness-indicating behavior but the individual boldness-score (the first principal component) obtained using principal component analysis combining all the measured behavioral responses did not explain vulnerability to experimental angling. Instead, large body size appeared as the only statistically significant predictor of capture probability. Our results suggest that angling is selective for large size, but not always selective for high boldness.

Intense selective hunting leads to artificial evolution in horn size

Article

Full-text available

Jan 2016
EVOL APPL

The potential for selective harvests to induce rapid evolutionary change is an important question for conservation and evolutionary biology, with numerous biological, social and economic implications. We analyze 39 years of phenotypic data on horn size in bighorn sheep (Ovis canadensis) subject to intense trophy hunting for 23 years, after which harvests nearly ceased. Our analyses revealed a significant decline in genetic value for horn length of rams, consistent with an evolutionary response to artificial selection on this trait. The probability that the observed change in male horn length was due solely to drift is 9.9%. Female horn length and male horn base, traits genetically correlated to the trait under selection, showed weak declining trends. There was no temporal trend in genetic value for female horn base circumference, a trait not directly targeted by selective hunting and not genetically correlated with male horn length. The decline in genetic value for male horn length stopped, but was not reversed, when hunting pressure was drastically reduced. Our analysis provides support for the contention that selective hunting led to a reduction in horn length through evolutionary change. It also confirms that after artificial selection stops, recovery through natural selection is slow. This article is protected by copyright. All rights reserved.

Does Angling Technique Selectively Target Fishes Based on Their Behavioural Type?

Article

Full-text available

Aug 2015
PLOS ONE

Recently, there has been growing recognition that fish harvesting practices can have important impacts on the phenotypic distributions and diversity of natural populations through a phenomenon known as fisheries-induced evolution. Here we experimentally show that two common recreational angling techniques (active crank baits versus passive soft plastics) differentially target wild largemouth bass (Micropterus salmoides) and rock bass (Ambloplites rupestris) based on variation in their behavioural tendencies. Fish were first angled in the wild using both techniques and then brought back to the laboratory and tested for individual level differences in common estimates of personality (refuge emergence, flight-initiation-distance, latency-to-recapture and with a net, and general activity) in an in-lake experimental arena. We found that different angling techniques appear to selectively target these species based on their boldness (as characterized by refuge emergence, a standard measure of boldness in fishes) but not other assays of personality. We also observed that body size was independently a significant predictor of personality in both species, though this varied between traits and species. Our results suggest a context-dependency for vulnerability to capture relative to behaviour in these fish species. Ascertaining the selective pressures angling practices exert on natural populations is an important area of fisheries research with significant implications for ecology, evolution, and resource management.

Vulnerability of individual fish to capture by trawling is influenced by capacity for anaerobic metabolism

Article

Full-text available

Aug 2015
Proc Biol Sci

The harvest of animals by humans may constitute one of the strongest evolutionary forces affecting wild populations. Vulnerability to harvest varies among individuals within species according to behavioural phenotypes, but we lack fundamental information regarding the physiological mechanisms underlying harvest-induced selection. It is unknown, for example, what physiological traits make some individual fish more susceptible to capture by commercial fisheries. Active fishing methods such as trawling pursue fish during harvest attempts, causing fish to use both aerobic steady-state swimming and anaerobic burst-type swimming to evade capture. Using simulated trawling procedures with schools of wild minnows Phoxinus phoxinus, we investigate two key questions to the study of fisheries-induced evolution that have been impossible to address using large-scale trawls: (i) are some individuals within a fish shoal consistently more susceptible to capture by trawling than others?; and (ii) if so, is this related to individual differences in swimming performance and metabolism? Results provide the first evidence of repeatable variation in susceptibility to trawling that is strongly related to anaerobic capacity and swimming ability. Maximum aerobic swim speed was also negatively correlated with vulnerability to trawling. Standard metabolic rate was highest among fish that were least vulnerable to trawling, but this relationship probably arose through correlations with anaerobic capacity. These results indicate that vulnerability to trawling is linked to anaerobic swimming performance and metabolic demand, drawing parallels with factors influencing susceptibility to natural predators. Selection on these traits by fisheries could induce shifts in the fundamental physiological makeup and function of descendent populations. © 2015 The Authors.

On r- and K−selection

Article

Jan 1970

E.R. Pianka

Consumptive Tourism Causes Timidity, Rather Than Boldness, Syndromes: A Response to Geffroy et al

Article

Dec 2015
TRENDS ECOL EVOL

Geffroy et al. [1] proposed that nature-based tourism reduces the fearfulness and antipredator behavior of animals, leading towards a boldness syndrome that elevates natural predation rates and could trigger cascading effects on populations and communities. We agree with the framework, hypotheses, and future research needs proposed in [1], but they apply strictly to nonthreatening human–wildlife interactions. However, nature-based tourism is often consumptive, where wild-living animals are chased, stressed, and eventually harvested in activities such as recreational fishing and hunting.

Fisheries-Induced Evolution

Article

Nov 2015
ANNU REV ECOL EVOL S

Beatriz Diaz Pauli

Increased mortality from fishing is expected to favor faster life histories, realized through earlier maturation, increased reproductive investment, and reduced postmaturation growth. There is also direct and indirect selection on behavioral traits. Molecular genetic methods have so far contributed minimally to understanding such fisheries-induced evolution (FIE), but a large body of literature studying evolution using phenotypic methods has suggested that FIE in life-history traits, in particular maturation traits, is commonplace in exploited fish populations. Although no phenotypic study in the wild can individually provide conclusive evidence for FIE, the observed common pattern suggests a common explanation, strengthening the case for FIE. This interpretation is supported by theoretical and experimental studies. Evidence for FIE of behavioral traits is limited from the wild, but strong from experimental studies. We suggest that such evolution is also common, but has so far been overlooked.

Behavioural variation in Eurasian perch populations with respect to relative catchability

Article

Feb 2016
ACTA ETHOL

Animal personalities, i.e. consistent individual differences in behaviour, are currently of high interest among behavioural and evolutionary biologists. The topic has received increasing attention also in fisheries science because selective harvesting of certain behavioural types might impose fishing-induced selection on personality. Here, we ice-fished wild Eurasian perch (Perca fluviatilis) from three native populations and investigated whether differences in relative catchability would explain behavioural differences observed in experimental conditions. We inferred relative catchability differences indirectly by fishing each location first with generally inefficient artificial bait and then by more efficient natural bait. The captured, individually tagged fish were tested in groups for their exploration tendency, activity and boldness under authentic predation risk in semi-natural stream channels. Fish that were easily captured first with artificial bait expressed fast exploration and acute activity, whereas the fish captured with natural bait showed less active and explorative behaviour. Differences in relative catchability did not explain variation in boldness or body size. In conclusion, we found that (1) Eurasian perch differing in relative catchability differ in certain behavioural traits, (2) fast explorers are more common among fish that get easily caught compared to fish that are more difficult to catch, (3) relative catchability explains more behavioural variation in a novel environment than in a familiar one and (4) selectivity of recreational angling on fish behaviour may depend on applied angling method and the effort spent on each location.

The evolutionary legacy of size-selective harvesting extends from genes to populations

Article

Apr 2015
EVOL APPL

Size-selective harvesting is assumed to alter life histories of exploited fish populations, thereby negatively affecting population productivity, recovery, and yield. However, demonstrating that fisheries-induced phenotypic changes in the wild are at least partly genetically determined has proved notoriously difficult. Moreover, the population-level consequences of fisheries-induced evolution are still being controversially discussed. Using an experimental approach, we found that five generations of size-selective harvesting altered the life histories and behavior, but not the metabolic rate, of wild-origin zebrafish (Danio rerio). Fish adapted to high fishing pressure invested more in reproduction, reached a smaller adult body size, and were less explorative and bold. Phenotypic changes seemed subtle but accompanied by genetic changes in functional loci. Thus, our results provided unambiguous evidence for rapid, harvest-induced phenotypic and evolutionary change when harvesting is intensive and size-selective. According to a life-history model, the observed life-history changes elevated population growth rate in harvested conditions, but slowed population recovery under a simulated moratorium. Hence, the evolutionary legacy of size-selective harvesting include populations that are productive under exploited conditions, but selectively disadvantaged to cope with natural selection pressures that often favor large body size.This article is protected by copyright. All rights reserved.

R-Selection and K-Selection

Article