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Introduction
Publications
Publications (58)
Det värdefulla med ämnesöverskridande utbildning får mer och mer stöd i didaktisk och pedagogisk forskning. Tvärdisciplinär undervisning uppmuntras, men det finns ännu få exempel på hur man pedagogiskt kan utforma undervisningen i praktiken. Vi ger här exempel på hur man i en tvärvetenskaplig utbildningspraktik kan arbeta med inkludering, interakti...
Why do animals display sexual ornaments – to attract mates, to compete for access to them, or both? In the broad-nosed pipefish (Syngnathus typhle), ornamented females commonly compete for access to males, whereas choosy males provide uniparental care. During courtship, females show a dynamic ornament, consisting of a row of dark B-shaped signs alo...
Higher education biology is often imagined, perceived, and described as having reached gender equality in terms of who gets to participate in disciplinary practices. However, like any other natural science discipline, higher education biology is a world whose landscapes are shaped by (re)productions of historical, cultural, and social norms. We exp...
Studying biology entails negotiating knowledges, identities, and what paths, more or less well‐trodden, to follow. Knowledges, identities, and paths within the very practices of science are fundamentally gendered and it is, therefore, critical to recognize when exploring students' learning and participation in natural sciences. Even though students...
Animal mating systems are fascinating and diverse, and their evolution is central to evolutionary biology. A mating system describes patterns and processes of how females and males mate and reproduce successfully, and how this relates to their reproductive ecologies, including demographic and environmental factors. One of the more stimulating chall...
Many organisms studied by evolutionary biologists have different sexes, and the evolution of separate sexes and sexual dimorphisms in morphology and behaviour are central questions in evolutionary biology. Considering scientists to be embedded in a social and cultural context, we are also subjected to the risk of gender-biased assumptions and stere...
Ecological specialization is an important engine of evolutionary change and adaptive radiation, but empirical evidence of local adaptation in marine environments is rare, a pattern that has been attributed to the high dispersal ability of marine taxa and limited geographic barriers to gene flow. The broad‐nosed pipefish, Syngnathus typhle, is one o...
In animals with uniparental care, the quality of care provided by one sex can deeply impact the reproductive success of both sexes. Studying variation in parental care quality within a species and which factors may affect it can, therefore, shed important light on patterns of mate choice and other reproductive decisions observed in nature. Using Sy...
A parent's nutritional state may influence its ability to provide care to offspring and ability to handle infections. In the broad-nosed pipefish, Syngnathus typhle, males care for their offspring by brooding the developing embryos in a brood pouch, providing nutrients and oxygen, resembling a pregnancy. Here, we demonstrate that the nutritional st...
Brain size varies greatly at all taxonomic levels. Feeding ecology, life history and sexual selection have been proposed as key components in generating contemporary diversity in brain size across vertebrates. Analyses of brain size evolution have, however, been limited to lineages where males predominantly compete for mating and females choose mat...
Trade-offs between brood size and offspring size, offspring survival, parental condition or parental survival are classic assumptions in life history biology. A reduction in brood size may lessen these costs of care, but offspring mortality can also result in an energetic gain, if parents are able to utilize the nutrients from the demised young. Ma...
Original data of the study.
All lengths and widths are in mm, all weights are in g.
(XLSX)
For animals that reproduce in water, many adaptations in life-history traits such as egg size, parental care, and behaviors that relate to embryo oxygenation are still poorly understood. In pipefishes, seahorses and seadragons, males care for the embryos either in some sort of brood pouch, or attached ventrally to the skin on their belly or tail. T...
The brain is one of the most energetically expensive organs in the vertebrate body. Consequently, the high cost of brain development and maintenance is predicted to constrain adaptive brain size evolution (the expensive tissue hypothesis, ETH). Here, we test the ETH in a teleost fish with predominant female mating competition (reversed sex roles) a...
Offspring fitness generally improves with increasing egg size. Yet, eggs of most aquatic organisms are small. A common but largely untested assumption is that larger embryos require more oxygen than they can acquire through diffusion via the egg surface, constraining egg size evolution. However, we found no detrimental effects of large egg size on...
The pipefish brood pouch presents a unique mode of parental care that enables males to protect, osmoregulate, nourish and oxygenate the developing young. Using a very fine O2 probe, we assessed the extent to which males of the broad-nosed pipefish (Syngnathus typhle) oxygenate the developing embryos and are able to maintain pouch fluid O2 levels wh...
In species that provide parental care, individuals should invest adaptively in their offspring in relation to the pre- and post-zygotic care provided by their partners. In the broad-nosed pipefish, Syngnathus typhle L., females transfer large, nutrient-rich eggs into the male brood pouch during mating. The male broods and nourishes the embryos for...
“Sex roles” are intuitively associated to stereotypic female and male sexual strategies and in biology, the term “sex role” often relates to mating competition, mate choice or parental care. “Sex role reversals” imply that the usual typological pattern for a population or species is deviates from a norm, and the meaning of “sex role reversal” thus...
Ingrid Ahnesjö recenserar:Retorik för naturvetare. Skrivande som fördjupar lärandet (2012), av Susanne Pelger & Sara Santesson, Studentlitteratur
The occurrence of male pregnancy in the family Syngnathidae (seahorses, pipefishes, and sea dragons) provides an exceptionally
fertile system in which to investigate issues related to the evolution of parental care. Here, we take advantage of this unique
reproductive system to study the influence of maternal body size on embryo survivorship in the...
In two experiments, radioactively labelled nutrients (either (3)H-labelled amino-acid mixture or (14)C-labelled glucose) were tube-fed to brooding male Syngnathus typhle. Both nutrients were taken up by the males and radioactivity generally increased in the brood pouch tissue with time. Furthermore, a low but significant increase of (3)H-labelled a...
In this study, the ovarian structure and mode of egg production were examined in two pipefishes, the broad-nosed pipefish Syngnathus typhle and the straight-nosed pipefish Nerophis ophidion, which show different types of polygamous mating patterns. Syngnathus typhle showed an ovary with one germinal ridge and asynchronous egg production, correspond...
Comparing five species of pipefish, egg size was significantly larger in species with brood pouches (Syngnathus typhle, Syngnathus acus and Syngnathus rostellatus) than in species without brood pouches (Entelurus aequoreus and Nerophis ophidion). Egg size correlated positively with female body size in species with brood pouches, but was similar acr...
We explored the effects of multiple mates on male reproductive success in a species with male parental care in which an increase
in the number of female mating partners does not increase the number of eggs received. The broad-nosed pipefish (Syngnathus typhle) has a polygynandrous mating system. In this species, the male cares for embryos in a spec...
The pipefishes (Syngnathidae) are marine teleosts in which the males brood the young. In some species sex-role reversal occurs when, contrary to the usual pattern, females compete more intensely than males for access to mates. This paper reports an investigation of the sex hormones of males and females to see whether they deviate from the "normal"...
Animal sex roles, in a wide sense, were the focus of a
stimulating post-symposium of the International Society of
Behavioral Ecology (ISBE) meeting in Perth 2010. The sex
roles symposium consisted of short presentations and an
hour of role-play designed to promote refreshed thinking and
discussion of “the ecology of sex roles”. In a strict sense, s...
Ingrid Ahnesjö received her Ph.D. at Uppsala University, Sweden, in 1989 in animal ecology with a thesis on sex-role reversals in pipefish. The author’s scientific fascination and curiosity still circles around the reproductive ecology of pipefishes (Syngnathidae) and includes mate choice, sexual selection, paternal care patterns, life history, and...
The differential allocation hypothesis assumes that animals should weigh costs and benefits of investing into reproduction with a current mate against the expected quality of future mates, and predicts that they should invest more into reproduction when pairing with a high-quality mate. In the broad-nosed pipefish (Syngnathus typhle), males care fo...
It is well known that many animals with placenta-like structures provide their embryos with nutrients and oxygen. However, we demonstrate here that nutrients can pass the other way, from embryos to the parent. The study was done on a pipefish, Syngnathus typhle, in which males brood fertilized eggs in a brood pouch for several weeks. Earlier resear...
The last several decades of research in behavioral ecology have resulted in a deeper appreciation of post-mating processes
and sexual conflict in sexual selection. One of the most controversial aspects of sexual selection is cryptic mate choice.
Here, we take advantage of male pregnancy in a sex-role-reversed pipefish (Syngnathus typhle) to quantif...
In the broad-nosed pipefish Syngnathus typhle, brooding males positioned themselves significantly more often towards the warmer part (18° C) of an aquarium, whereas females were indifferent in this respect. This behavioural temperature preference may increase male brooding rate and indirectly influence patterns of mating competition.
Fishes show a fascinating diversity in mating systems and reproductive behaviours. Furthermore, various traits that seem to have evolved under sexual selection, like elongated fins, gaudy coloration, courtship, sounds and parental care behaviours, are widespread. In the environment that fishes live in, numerous factors may cause variation in sexual...
In the pipefish Syngnathus typhle L. parental care is exclusively paternal. Males brood embryos in a brood pouch for about a month, providing nutrients and oxygen. The newborn juveniles are free-swimming and no further care is provided. The influence of paternal length and number of newborn on juvenile weight and growth rate, and how in turn the la...
A phenomenon that has attracted a substantial theoretical and empirical interest is the positive relationship between egg size and the extent of parental care in fishes. Interestingly, despite the effort put into solving the causality behind this relationship over the past two decades it remains largely unsolved. Moreover, how general the positive...
Modern theory predicts that relative parental investment of the sexes in their young is a key factor responsible for sexual selection. Seahorses and pipefishes (family Syngnathidae) are extraordinary among fishes in their remarkable adaptations for paternal care and frequent occurrences of sex-role reversals (i.e., female-female competition for mat...
Covering sex allocation, sex determination and operational sex ratios, this multi-author volume provides both a conceptual context and an instruction in methods for many aspects of sex ratio research. Theory, statistical analysis and genetics are each explained and discussed in the first three sections. The remaining chapters each focus on research...
The potential reproductive rate (PRR), which is the offspring production per unit time each sex would achieve if unconstrained by mate availability, often differs between the sexes. An increasing sexual difference in PRR predicts an intensified mating competition among the sex with the higher PRR. The use of PRR can provide detailed predictions of...
In contrast to the majority of vertebrate species, primary male parental care is common in fishes and encompasses a remarkable diversity of adaptations. Seahorses and pipefishes (Family Syngnathidae) exhibit some of the most specialized forms of paternal care in animals and so are ideally suited to the study of the evolution of male parental care....
We studied how male fifteen-spined sticklebacks, Spinachia spinachia, vary in paternal competence, whether males advertise their competence and whether females prefer better fathers. In this species the male alone provides care for the offspring through nest building, fanning, cleaning and protecting the eggs. We found no female preference for larg...
In sexually reproducing animals, individuals of one sex may have to compete for access to mating partners of the opposite sex. The operational sex ratio (OSR) is central in predicting the intensity of mating competition and which sex is competing for which. Thanks to recent theoretical and empirical advances, particularly by exploring the concept o...
Embryo success was studied in the paternally brooding pipefish Syngnathus typhle. During brooding, which lasts about a month, males provide embryos in their brood pouch with nutrients and oxygen via a placenta-like
structure. Egg size depends on female size. In aquaria, males were mated with differently sized females to give the following
treatment...
Synopsis Pipefishes have rarely been watched in the wild and have never before been followed in their common seagrass habitats. This study explores the reproductive ecology of five species of pipefishes living in a Swedish eelgrass meadow during parts of four breeding seasons, tagging four of the species. Pipefish are remarkable for their specialis...
The differences in potential reproductive rate between the sexes can be used to predict the operational sex ratio and the
patterns and intensity of mating competition and hence sexual selection in a population. This article describes how one environmental
component, temperature, affects potential reproductive rates of the two sexes in the paternall...
In the pipefish Syngnathus typhle, only males brood embryos in specially developed brood pouches, supplying oxygen and nutrients. Laboratory studies have shown that this elaborate paternal care has led to sex-role reversal in this species: males limit female reproductive rate, females are the primary competitors for mates and males exercise greater...
The male pregnancy of pipefishes and seahorses has led to the inference that females compete most intensely for access to mates, because males limit female reproduction. However, recent work has shown that in different species either sex may be the predominant competitor for mates. In this family, there is an apparent association between the mating...
1. In the pipefish Syngnathus typhle sex roles are reversed, as females compete for access to males. In this species males provide all brood care (i.e. are `pregnant') and female reproductive rate exceeds the reproductive rate of males. Consequently females are limited by access to mates and male reproductive success is limited by male brooding abi...
In Syngnathus typhle males brood embryos in a brood pouch for about a month, providing nutrients and oxygen. The newborn juveniles are free-swimming and no further care is provided. Paternal length is significantly and positively correlated to weight of newborn, weight of a two-week-old juvenile and juvenile growth rate. Number of newborn is correl...