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Colonization and extinction of land planarians (Platyhelminthes, Tricladida) in a Brazilian Atlantic Forest regrowth remnant

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Long-term assessments of species assemblages are valuable tools for detecting species ecological preferences and their dispersal tracks, as well as for assessing the possible effects of alien species on native communities. Here we report a 50-year-long study on population dynamics of the four species of land flatworms (Platyhelminthes, Tricladida, Terricola) that have colonized or become extinct in a 70-year-old Atlantic Forest regrowth remnant through the period 1955–2006. On the one hand, the two initially most abundant species, which are native to the study site, Notogynaphallia ernesti and Geoplana multicolor have declined over decades and at present do not exist in the forest remnant. The extinction of these species is most likely related with their preference for open vegetation areas, which presently do not exist in the forest remnant. On the other hand, the neotropical Geoplaninae 1 and the exotic Endeavouria septemlineata were detected in the forest only very recently. The long-term study allowed us to conclude that Geoplaninae 1 was introduced into the study area, although it is only known from the study site. Endeavouria septemlineata, an active predator of the exotic giant African snail, is originally known from Hawaii. This land flatworm species was observed repeatedly in Brazilian anthropogenic areas, and this is the first report of the species in relatively well preserved native forest, which may be evidence of an ongoing adaptive process. Monitoring of its geographic spread and its ecological role would be a good practice for preventing potential damaging effects, since it also feeds on native mollusk fauna, as we observed in lab conditions.
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ORIGINAL PAPER
Colonization and extinction of land planarians
(Platyhelminthes, Tricladida) in a Brazilian Atlantic
Forest regrowth remnant
Fernando Carbayo ÆJu
´lio Pedroni Æ
Eudo
´xia Maria Froehlich
Received: 1 October 2007 / Accepted: 23 October 2007 / Published online: 8 November 2007
ÓSpringer Science+Business Media B.V. 2007
Abstract Long-term assessments of species assem-
blages are valuable tools for detecting species
ecological preferences and their dispersal tracks, as
well as for assessing the possible effects of alien
species on native communities. Here we report a 50-
year-long study on population dynamics of the four
species of land flatworms (Platyhelminthes, Tricladi-
da, Terricola) that have colonized or become extinct
in a 70-year-old Atlantic Forest regrowth remnant
through the period 1955–2006. On the one hand, the
two initially most abundant species, which are native
to the study site, Notogynaphallia ernesti and Geo-
plana multicolor have declined over decades and at
present do not exist in the forest remnant. The
extinction of these species is most likely related with
their preference for open vegetation areas, which
presently do not exist in the forest remnant. On the
other hand, the neotropical Geoplaninae 1 and the
exotic Endeavouria septemlineata were detected in
the forest only very recently. The long-term study
allowed us to conclude that Geoplaninae 1 was
introduced into the study area, although it is only
known from the study site. Endeavouria septemline-
ata, an active predator of the exotic giant African
snail, is originally known from Hawaii. This land
flatworm species was observed repeatedly in Brazil-
ian anthropogenic areas, and this is the first report of
the species in relatively well preserved native forest,
which may be evidence of an ongoing adaptive
process. Monitoring of its geographic spread and its
ecological role would be a good practice for
preventing potential damaging effects, since it also
feeds on native mollusk fauna, as we observed in lab
conditions.
Keywords Free-living terrestrial flatworms
Neotropical Native Introduced and exotic species
Invasion Urban forest
Introduction
Some invasive species often remain initially unno-
ticed due to their cryptic habits (Mu
¨ller and Griebeler
2002) or the lag-time preceding their expansion
(Simberloff and Gibbons 2004). Short-term assess-
ments have been shown to possibly be inadequate to
describe ecological findings and the roles that exotic
species play over time in the areas they invade
(Strayer et al. 2006; Hobbie et al. 2003).
Ju
´lio Pedroni: Granted by CNPQ–Brazil.
F. Carbayo (&)J. Pedroni
Escola de Artes, Cie
ˆncias e Humanidades (EACH),
Universidade de Sa
˜o Paulo (USP), Av. Arlindo Bettio,
1000, Sa
˜o Paulo, SP 03828-000, Brazil
e-mail: baz@usp.br
E. M. Froehlich
Departamento de Zoologia, Universidade de Sa
˜o Paulo
(USP), Rua do Mata
˜o, trav. 14, no 321, Cidade
Universita
´ria, Sa
˜o Paulo, SP 05508-900, Brazil
123
Biol Invasions (2008) 10:1131–1134
DOI 10.1007/s10530-007-9190-1
The geographical distribution of a few land
flatworms (Platyhelminthes, Tricladida, Terricola)
has been expanded throughout the globe by human
mediation (Ducey et al. 2005). Studies on the intro-
duction and dispersal of a few Australasian flatworm
species raised concerns since they seem to affect soil
ecosystems and may be responsible for the reduction
of the diversity of invertebrate native fauna, where
they may become pests (Fiore et al. 2004; Greenslade
et al. 2007).
A number of native and a few exotic land
planarian species are common in anthropogenic
forests and gardens scattered in the city of Sa
˜o Paulo,
Brazil. Here we focus on colonization and extinction
events undergone by four land planarian species over
50 years in a Brazilian Atlantic forest regrowth
remnant.
Material and methods
Study area
The municipality of Sa
˜o Paulo, Brazil has a well
defined summer or rainy season and a very dry winter
from May to September. The University campus
‘Armando de Salles Oliveira’’ belongs to the Uni-
versity of Sa
˜o Paulo, and is located 23°330S and
46°430W at 795 m altitude, inside the city. The
campus is 417 ha, originally covered by dense
Brazilian Atlantic ombrophilous forest. In the century
XIX most of its area was occupied by settlement and
grass field for cattle grazing, with a remained small
valley covered with secondary forest. In the 1950s the
area passed to be part of the University of Sa
˜o Paulo,
where building and gardening initiatives began. At
present, the area is occupied by buildings, gardens, a
plant nursery, and a variety of non-native forests,
with the exception of the small valley, the so-called
Forest Reserve (locally, Reserva do Mata
˜o) which is
a 70-year-old regrowth forest remnant with about
10 ha.
Field methods
In the period of 1955–1992, field-work was conducted
by Froehlich et al. for faunistic inventory purposes. A
total of 37 samples were randomly taken by 1–3 people
throughout the total extension of the Forest Reserve,
without plotting, lasting from 30 min to 3 h. To assess
the present habitat preference and species assemblage,
three plots of *60 m
2
each were selected, two in the
most central area of the Forest Reserve, where the
oldest vegetation stands (plots 1 and 2) and a third one
in the East edge of the Forest Reserve (plot 3). Twenty
samples were taken (*twice a month) between
September 2005 and March 2006. In each sampling
session, land planarians were searched for during the
day in each plot for 15 min. Animals were searched
in situ for in the soil litter, and underneath and inside
fallen logs and branches.
Results and discussion
We focus on the four species that have colonized
or become extinct in the study site through the period
1955–2006 (Table 1). On the one hand, two
species—Notogynaphallia ernesti Leal-Zanchet &
EM Froehlich, 2006 and Geoplana multicolor Graff,
1899—were initially very abundant from 1955 until
1958, whereupon they were clearly in decline, and in
2005–2006 they were not observed in the Forest
Reserve. On the other hand, Geoplaninae 1 and
Endeavouria septemlineata (Hyman, 1939) were
observed only very recently (2005–2006). Geoplan-
inae 1 is at present abundant, with most individuals
found in the forest border (plot 3). The only sited
individual of E. septemlineata was found in plot 2.
Local extinctions
Why did Notogynaphallia ernesti and Geoplana
multicolor become extinct? The known records of
N. ernesti date from the late 1940s. The species were
observed mainly in open vegetation areas and gardens
in the Sa
˜o Paulo town and other cities of the states of
Sa
˜o Paulo and Parana
´(Southern Brazil), where the
species is still common, including the University
campus. These registers suggest that it prefers open
vegetation, as previously reported (Carbayo et al.
2002), and that its decline in the Forest Reserve could
be caused by the progressive thickening of the forest.
Geoplana multicolor was also not observed
recently in the Forest Reserve. However, differently
from N. ernesti, it almost has disappeared from the
University campus, where until the 1960s it was
1132 F. Carbayo et al.
123
abundant (up to 30 individuals were to be found in
one day) in areas covered with bushes (EMF, pers.
obs.). The causes for the extinction of G. multicolor
in the Forest Reserve, and rarefaction in the Univer-
sity campus, could be related with its apparent
preference for closed bushy environments, but it is
not able to easily survive in gardened areas, nor
inside mature and dense forests.
Local colonizations
Man-mediated dispersion of land planarians was
related to transport of hardy plants or building
materials (Hyman 1940; Christensen and Mather
1998). Geoplaninae 1 (Geoplanidae) and Endeavou-
ria septemlineata (Geoplanidae, Caenoplaninae) were
only observed in the Forest Reserve after 50 years of
sampling. Both species have been introduced into the
Forest Reserve, with man being their most likely
vector.
Geoplaninae 1 belongs to the neotropical fauna
and is only known to be present in the University
campus. It was first seen in the plant nursery (1965,
EMF, pers. obs.), where the species probably arrived
to the campus through plant exchange. Since 1969, it
has been repeatedly located in gardens around
buildings in the campus. The species was found in
the Forest Reserve very recently (in 2005–2006), and
could be acclimating to the Forest Reserve after
recent man-mediated introduction from the plant
nursery located in the University campus. Although
there is no track of its origin, this long-term study
allowed us to detect the neotropical Geoplaninae 1 as
an introduced species to the study site.
Endeavouria septemlineata is an exotic species,
first described from Hawaii and also reported for
Australia. In the University campus, it was recorded
for the first time in 1986 in gardens around buildings
with dense populations. In the existing plant nursery
in the University campus it was first collected in
Table 1 Number of samplings per year and abundance of the four species of land planarians (Platyhelminthes, Tricladida) studied in
the forest reserve
Year Number of
samplings
Notogynaphallia
ernesti
Geoplana
multicolor
Geoplaninae 1 Endeavouria
septemlineata
Number of
individuals
1955 5 53 23 81
1956 3 12 10 25
1958 2 10 22 34
1961 1 – – 1
1962 1 3 – – 4
1963 1 1 1 – 3
1965 1 9 – 10
1969 1 1 – – 2
1971 1 1 – – 2
1972 1 – – 1
1976 2 1 – 3
1977 11 1 – – 12
1980 1 – – 1
1985 2 1 – – 3
1986 1 3 – – 4
1987 1 – – 1
1989 1 – – 1
1992 1 1 1 – 3
2005–2006 (plot 1) 20 1 21
2005–2006 (plot 2) 20 2 1 23
2005–2006 (plot 3) 20 11 31
Number of individuals 87 67 14 1 169
Colonization and extinction of land planarians 1133
123
1989. It has been continuously present from the
1980s in the city of Sa
˜o Paulo (EMF, per. obs.), and it
is found frequently in some parks and city waste
lands of other Brazilian towns, Campo Grande (MS),
Floriano
´polis (SC), Maquine
´(RS), Sa
˜o Lourenc¸o do
Sul (RS) (EMF; FC, pers. obs.). The species is an
active predator of the giant African snail Achatina
fulica Bowdich in Hawaii (Mead 1963), and accord-
ingly it accepted snails and smashed native slugs in
laboratory conditions (FC and R. Arau
´jo, per. obs.).
This is the first record of E. septemlineata inhab-
iting the Brazilian Atlantic ombrophilous forest,
which may be evidence of an ongoing adaptive
process. It raises concerns of its potential damaging
effects on the local fauna on which it feeds, as
reported for other land planarians elsewhere (Sch-
rader and Unger 2003; Ducey et al. 2007).
Motivation to study invasions usually only arises
after they have spread extensively, and only in
species that already seem to be having an impact
(Parker et al. 1999). It would be a good preventive
practice to trace the evolution of the population of
E. septemlineata in the Forest Reserve and to study
potential interferences with the native fauna, espe-
cially its preys and species competitors for food
resources.
Acknowledgments We thank W. Mantovani (USP) for the
description of the vegetation in the study area; J. S. Morgante
(USP) for the sampling license in the Forest Reserve;
M. T. Rodrigues (USP) for facilities to use the histological
laboratory; CNPq for the research grant PIBIC provided to JP;
and J. Grau and J. Hesson for English revision of the
manuscript.
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... FROEHLICH, E.M. 2008. State of knowledge of the macroturbellarians (Platyhelminthes) from Brazil. ...
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Invasive species establish successfully in new habitats especially due to their generalist diet and release of natural enemies. However, native species may also adapt to use new elements in their ecosystem. The planarian Endeavouria septemlineata, first recorded in Hawaii, was later registered in Australia and Brazil. Recently we found it in human-disturbed areas in southern Brazil and here we investigate its interactions with other invertebrates both in the field and in the laboratory. We observed the species in the field during collecting activities and maintained some specimens alive in small terraria in the laboratory, where we offered different invertebrate species as potential prey and also put them in contact with native land planarians in order to examine their interaction. Both in the field and in the laboratory, E. septemlineata showed a gregarious behavior and was found feeding on woodlice, millipedes, earwigs and gastropods. In the laboratory, specimens did not attack live prey, but immediately approached dead specimens, indicating a scavenging behavior. Four native land planarians of the genus Obama and two of the genus Paraba attacked and consumed E. septemlineata, which, after the beginning of the attack, tried to escape by tumbling or using autotomy. As a scavenger, E. septemlineata would impact the populations of species used as food, but could possibly exclude native scavengers by competition. On the other hand, its consumption by native land planarians may control its spread and thus reduce its impact on the ecosystems.
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A recent survey of the literature and databases on turbellarian fauna from the State of Sao Paulo, Brazil, yielded a total of 312 species (including Acoelomorpha, a new phylum) inhabiting marine, as well as freshwater, and terrestrial habitats. In 1999, approximately 333 species were registered. This higher number is related to a number of species synonymized thereafter, and probably related to lower accuracy of prior accounts. Nonetheless, the only two taxonomists studying this animal group in the State estimated a much higher actual number of species. In the State there are three scientific collections containing turbellarians, almost exclusively from terrestrial habitats.
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Land flatworms are carnivorous, mainly predators. However, knowledge on their predatory behavior and prey preference is very scarce. This paucity of data is a limiting factor in the study of their biology and organismal ecology, resulting in a very difficult task to breed them in the laboratory for prolonged periods if prey preference and predation frequency are unknown. We investigated the predatory behavior of Notogynaphallia abundans (Graff, 1899), Geoplaninae, based on laboratory experiments. In order to determine its predatory choices, we offered mollusks, earthworms, arthropods, and other land flatworms. Only land isopods were accepted, with an average consumption of 3.4 individuals per week. Linear regression showed a positive relationship between the number of consumed isopods and the increase/decrease in body mass. Consumption resulting in an increase in body mass was ca. four isopods per week. Predatory behavior, with a mean time-span of 28 min 45 s ± 15 min 47 s, includes encounter and capture of prey, immobilization, handling and feeding. Variation in the duration of this activity in N. abundans is clearly due to variations in the time necessary for transferring the prey from either the anterior or posterior thirds of the body to the mouth, as well as for external digestion and ingestion. In order to capture very active and fast-moving animals such as land isopods, N. abundans employs various strategies, using either the anterior or the posterior body regions to press the prey against the ground or against its own body, thus allowing it to deal with various responses by the prey, and thereby maximizing predatory success. Similar to other flatworms, both physical holding and entrapment in a mucous secretion are of fundamental importance for prey-immobilization. The different strategies employed by land flatworms in their predatory behavior are discussed, and behavioral plasticity in the capture and immobilization of prey in different platyhelminth.
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An increasing number of exotic terrestrial planarian species have established populations worldwide. In North America, the most prominent invasive flatworms are three members of the broadhead planarian genus Bipalium. Herein we report observations on the morphology, predatory behavior, and reproduction of Bipalium cf. vagum, new to this continent and report its occurrence in Florida and Texas. Individuals of this species have a distinctive combination of head shape and pattern of dark dorsal pigmentation (large head spots, complete collar, and prominent median stripe) that distinguishes them from other members of the genus. Although the other North American species of Bipalium feed on earthworms, B. cf. vagum feeds exclusively on terrestrial mollusks. Their predatory behavior includes following mucus trails and subduing the prey by capping the prey's head with the flatworm's anterior end and wrapping the prey's foot in the body of the planarian. Members of this species reproduce via egg capsules that contain small numbers of offspring. Because this is the first land planarian reported in North America that is a predator of mollusks, native land snails and slugs are unlikely to have effective defenses against it. Therefore, we should continue to monitor its geographic spread and potential ecological impact.
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The 24 projects of the National Science Foundation's Long Term Ecological Research Network, whose sites range from the poles to the Tropics, from rain forests to tundras and deserts, and from offshore marine to estuarine and freshwater habitats, address fundamental and applied ecological issues that can be understood only through a long-term approach. Each project addresses different ecological questions; even the scale of research differs across sites. Projects in the network are linked by the requirement for some research at each site on five core areas, including primary production, decomposition, and trophic dynamics, and by cross-site comparisons, which are aided by the universally available databases. Many species and environmental variables are studied, and a wide range of synthetic results have been generated.
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Although ecologists commonly talk about the impacts of nonindigenous species, little formal attention has been given to defining what we mean by impact, or connecting ecological theory with particular measures of impact. The resulting lack of generalizations regarding invasion impacts is more than an academic problem; we need to be able to distinguish invaders with minor effects from those with large effects in order to prioritize management efforts. This paper focuses on defining, evaluating, and comparing a variety of measures of impact drawn from empirical examples and theoretical reasoning. We begin by arguing that the total impact of an invader includes three fundamental dimensions: range, abundance, and the per-capita or per-biomass effect of the invader. Then we summarize previous approaches to measuring impact at different organizational levels, and suggest some new approaches. Reviewing mathematical models of impact, we argue that theoretical studies using community assembly models could act as a basis for better empirical studies and monitoring programs, as well as provide a clearer understanding of the relationship among different types of impact. We then discuss some of the particular challenges that come from the need to prioritize invasive species in a management or policy context. We end with recommendations about how the field of invasion biology might proceed in order to build a general framework for understanding and predicting impacts. In particular, we advocate studies designed to explore the correlations among different measures: Are the results of complex multivariate methods adequately captured by simple composite metrics such as species richness? How well are impacts on native populations correlated with impacts on ecosystem functions? Are there useful bioindicators for invasion impacts? To what extent does the impact of an invasive species depend on the system in which it is measured? Three approaches would provide new insights in this line of inquiry: (1) studies that measure impacts at multiple scales and multiple levels of organization, (2) studies that synthesize currently available data on different response variables, and (3) models designed to guide empirical work and explore generalities.
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The introduction of several plant pests into Europe in the 19th century with disastrous consequences called for the development of plant quarantine measures to prevent the spread and introduction of pests of plants and plant products. With the purpose of harmonising these measures, and of promoting measures for pest control, the International Plant Protection Convention (IPPC) was developed to address organisms that are both directly and indirectly injurious to plants. It supplies a framework for measures against invasive alien species according to the Convention on Biological Diversity, as far as they are plant pests. Three examples of invasive alien species within the scope of the IPPC are given in the article: the fungus Ceratocystis fagacearum, the pinewood nematode Bursaphelenchus xylophilus and the flatworm Arthurdendyus triangulatus. In its 1997 revision, the IPPC provides for the establishment of International Standards for Phytosanitary Measures, being acknowledged by the Agreement on the Application of Sanitary and Phytosanitary Measures of the World Trade Organisation. Standards most important for invasive alien species are those on pest risk analysis, on requirements for the establishment of pest-free areas, on surveillance, on pest eradication programmes, and on the import and release of exotic biological agents. Phytosanitary regulations in the European Union (EU) have been harmonised and up to now have regulated about 300 plant pests. The requirements also have a protective horizontal effect against the unintentional introduction of many other species, but the existing broader IPPC mandate for alien plant pests is not fully applied by the EU regulations.
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Invasive species are a serious threat to biodiversity worldwide. The relatively simple ecological systems of the subantarctic have the potential to be significantly damaged by predatory species that invade. Two species of exotic, predatory, terrestrial flatworms were first collected in 1997 from two localities only 2km apart, in the southeast of subantarctic Macquarie Island. The species were later identified as Kontikia andersoni and Arthurdendyus vegrandis. We report here the results of fieldwork in 2004 that established that both species now occupy about a seventh of the southeast of the island which has a total area of only 170km2 and that there seem to be no barriers to further expansion. The island was first discovered in 1810 and so it is likely the species were introduced by means of human intervention within the last 200years. We provide evidence to show that both species originated in New Zealand and have probably been on the island for ∼100years giving an average rate of spread of about 10m per year. Other species of Arthurdendyus have been introduced from New Zealand to the United Kingdom where they prey on earthworms. The quarantine significance of A. vegrandis for Australia is discussed and recommendations made to reduce the probability of it entering Tasmania where it has the potential to become an agricultural pest.
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Terrestrial flatworms, or Terricola, are sensitive to environmentalchanges and therefore might be excellent indicators of the conservation statusof natural habitats. The present study aimed to answer two main questions: (1)is terrestrial planarian diversity affected by human disturbances, and (2) isthere any species or group of species that indicates such disturbance? The studysite, National Forest of So Francisco de Paula, Brazil, was originallycovered by a mixed ombrophilous forest, but successive reforestations andselective logging have modified the original landscape. We studied Terricoladiversity in the four main habitats in the study area: mixed ombrophilous forest(NA), ombrophilous forest with selective Araucariaangustifolia logging (N), A. angustifoliareforestation (A), and reforestation of Pinus elliottii(P). According to an increasing degree of disturbance, the habitats might beordered as follows: (NA)Geoplana franciscana,Geoplana sp. 5, and possibly Geoplanidae 3 andNotogynaphallia guaiana) that prefer habitats located onthe extreme right along the main axis of a detrended correspondence analysisordination and therefore can be considered as indicators of well preserved,natural habitats. On the other hand there are species(Xerapoa sp. 1, Choeradoplanaiheringi, G. marginata sensu Marcus andGeoplana sp. 2) preferring more disturbed habitats, whichmay form biological indicators of such disturbances.
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The 24 projects of the National Science Foundation's Long Term Ecological Research Network, whose sites range from the poles to the Tropics, from rain forests to tundras and deserts, and from offshore marine to estuarine and freshwater habitats, address fundamental and applied ecological issues that can be understood only through a long-term approach. Each project addresses different ecological questions; even the scale of research differs across sites. Projects in the network are linked by the requirement for some research at each site on five core areas, including primary production, decomposition, and trophic dynamics, and by cross-site comparisons, which are aided by the universally available databases. Many species and environmental variables are studied, and a wide range of synthetic results have been generated.
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Substantial populations of invasive non-indigenous species occasionally collapse dramatically. Although disease is often invoked, the causes are rarely studied experimentally and/or quantitatively, and some collapses remain quite mysterious. The widespread invasive snail Achatina fulica and pondweed Elodea canadensis appear to be characterized by rapid expansion followed by rapid decline. For the former species, disease may be the proximal cause of the collapse, while repeated collapse of the latter species is unexplained. Several other widely cited collapses of introduced species may simply be temporary lows during a more or less regular boom-and-bust cycle. However, on a restricted site (such as a small island), a boom-or-bust cycle may be impossible and recovery may never ensue; local extinction may even occur. In several instances, apparently spontaneous crashes were in fact probably caused by subsequently introduced competitors. Except for the few species in which spontaneous collapse has been repeatedly observed, the possibility of such an event is unwarranted as a potential rationale for a do-nothing approach to management. For such species, even if a crash ultimately occurs, the species may already have caused persistent ecological damage.
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Comparisons between invasive species and their relatives can help in identifying traits that facilitate dispersal and colonization, and comparisons among populations within invasive species may highlight the roles of plasticity and evolutionary adaptation. Bipalium adventitium Hyman 1943 is an exotic, earthworm-eating soil flatworm that has become widespread and abundant in North America. As a first step in better understanding the ecology and evolution of this invasive planarian, we studied its reproductive traits in populations across its extensive geographic range and conducted an experiment on the effects of food availability. Colonization by B. adventitium is facilitated by hermaphroditism, sperm storage, and tough egg capsules containing multiple offspring, traits present in most Terricola. The egg capsules produced by B. adventitium were large (22.5 mg), hatched in 7–37 days (mean=23 days), contained 1–8 offspring (mean=3.4), and represented about 21% of a parent's predeposition mass. Many individuals produced multiple egg capsules. Although considerable intraspecific variation was detected for most reproductive parameters, significant differences among geographic populations were noted for egg capsule mass, mean offspring mass, and measures of total reproductive output. Intraspecific correlations between parent mass and the masses of egg capsules and offspring, and the results of our experiment showing that food availability affected egg capsule production, together suggest that thus far intra-population variation and plasticity have been more important than local evolutionary adaptation in the invasion of this species.