Reproductive variation and the egg size-clutch size trade-off within and among populations of painted turtles (Chrysemys picta bellii)

Interpopulation variation in egg size, clutch size and clutch mass was studied 3 years in four populations of painted turtles (Chrysemys picta bellii) from western Nebraska. Body size varied among all populations and was larger in two large (56–110 ha), sandhills lake populations than in two populations in smaller habitats (1.5–3.6 ha) of the Platte River floodplain. Reproductive parameters (egg mass, clutch mass, and clutch size) generally increased with maternal body size within populations. Clutch wet and dry mass varied among populations but largely as a function of maternal body size. Clutch size was largest in the sandhills lake populations, both absolutely and relative to maternal body size. Egg mass was smallest in the sandhills lakes and varied annually in one population. Over all populations, an egg sizeclutch size trade-off was detected (a negative correlation between egg mass and clutch size) after statistically removing maternal body size effects. Egg wet mass and clutch size were negatively correlated over all years within the sandhills populations and in some years in three populations. Although egg size varied within populations, egg size and clutch size covaried as expected by optimal offspring size models. Thus, patterns of egg size variation should be interpreted in the context of proximate or adaptive maternal body size and temporal effects. Comparisons among populations suggest that large egg size relative to maternal body size may occur when juvenile growth potential is poor and mean maternal body size is small.     

Fish community composition and diversity at restored estuarine habitats in Tampa Bay,Florida, United States

Estuary restoration in Tampa Bay, Florida, United States, is an ongoing focus of natural resource managers because of pressure from an increasing coastal population, historic habitat loss, and restoration's importance to economic development, recreational activities, and fish habitat. A growing population can also limit future large‐scale restorations due to associations with cost and land availability. This limitation might be overcome by applying the habitat mosaic approach to restoration, which creates distinct habitat types at small spatial scales. This approach was applied to create three types of estuarine habitat, reconnected tidal creek, salt marsh, and tidal pond. The objectives of this study were to (1) initiate monitoring of a restored wetland mosaic and (2) determine how fish diversity and community structure vary among restored habitat types. Replicated sampling using a 3‐mm mesh seine was used to characterize the fish communities. Our results indicate that the habitat mosaic approach creates suitable habitat for a variety of fish species where 37% of fish species were captured in just one habitat type. In particular, the recreationally important Centropomus undecimalis (common snook) was more common in the mangrove‐lined creek and the non‐native Sarotherodon melanotheron (blackchin tilapia) was common in the tidal pond. Greater emphasis should be placed on applied restoration research to identify how habitat types within a larger restoration mosaic contribute to local species diversity and recreationally and commercially important fishes, while limiting non‐natives. This emphasis could reveal how restoration approaches can be modified to include habitat mosaics, maximizing their contribution to productive fish habitat.     

Life-history variation in closely related generalist predators living in the same habitat: a case study with three Cyclosa spiders

1. Generalist predators sharing similar food resources and phenologies as well as having no competitive interactions are expected to have a similar life-history pattern, but some closely related web spiders show different life-history traits. The present paper clarifies possible selection pressures affecting life-history traits of the three coexisting Cyclosa spiders and explores the significance of the life-history variation.
2. Cyclosa argenteoalba had lower daily survival rate and higher growth rate, C. sedeculata had higher daily survival rate and lower growth rate, and C. octotuberculata showed intermediate levels. This implies that the selection pressures these spiders experience differ appreciably even in the same habitat.
3. The significance of the life-history characteristics of the three species was evaluated by general life-history theories. Cyclosa argenteoalba showed distinguishing reproductive traits: shorter time to maturation, larger reproductive effort, larger relative clutch size, decreased clutch size with the number of clutches, and smaller egg size. These characteristics may have evolved in response to the larger ratio of juvenile to adult survivorship. Cyclosa octotuberculata had a clutch size much larger than the other two species, but relative clutch sizes accounting for body size were similar between C. octotuberculata and C. sedeculata . Also, the two species showed a similar time to maturation despite having different selection pressures. Probably, higher growth rate compensates for lower survivorship, leading to the similarity in some reproductive traits.     

The influence of territory characteristics and food supply on the breeding performance of the Red-backed Shrike (<Emphasis Type="Italic">Lanius collurio</Emphasis>) in an extensively farmed region of eastern Poland

The breeding performance of the Red-backed Shrike (Lanius collurio) in relation to the territory characteristics was investigated. The study was conducted in an area of high agricultural land use, characterised by small field size, a more mosaic habitat and low use of mineral fertilisers in comparison to Western European countries. The influence of habitat structure and composition in the territory on the date of clutch initiation, nest predation and clutch size in the Red-backed Shrike was not found, but such an influence on the number of nestlings was shown. The minimum adequate model explained 18.3% of the variation between territories in nestling’s number. The number of fledglings was positively correlated with the area of pastures, meadows, orchards and fallows within territories, and negatively correlated with length of overhead transmission lines. The number of fledglings was correlated with food abundance within territories, based on to the results from pitfall traps. There was no correlation between territory food abundance and the size of clutch. The presence of pastures, meadows and fallows, which are foraging places, thus seems to be crucial for the protection of the Red-backed Shrike.     

Geographical variation in egg size of the Great Tit Parus major: a new perspective

A recent study on geographical variation in egg size of Great Tits Parus major concluded that: (1) mean egg size tended to increase with increasing latitude; and (2) mean egg size was positively correlated with mean clutch size. Including new data on both egg and clutch size, we reanalysed the relationships between egg size, clutch size and latitude, and investigated the possible effects of habitat type, female body size and egg shape on these relationships. We found that (1) egg volume showed minimum values around 51°N, increasing both north and southwards; (2) female body size increased linearly with increasing latitude; (3) female body size was positively correlated with egg breadth, but not with egg length or egg volume; (4) the sphericity index of the eggs (breadth to length ratio) was largest at medium latitudes, and eggs were more elongated towards the north and the south; (5) the relationship between clutch size and latitude was curvilinear, with the largest clutch sizes at intermediate latitudes; (6) egg size was not correlated with clutch size when the complete latitudinal range was considered, but egg size was negatively correlated with clutch size between 40 and 51°N; and (7) egg size did not differ among habitat types. We suggest that female body size (which probably limits egg breadth), and the pressure for producing large eggs (which in turn increases the reproductive success) are the main determinants of geographical variation in egg size and shape. Populations of small-bodied Great Tits seem to escape from the limits of their size, producing relatively elongated eggs, so that from a certain latitude southwards, egg volume does not decrease in spite of a decrease in female body size. Moreover, the negative relationship between egg and clutch size at low latitudes suggests that energetic trade-offs may also contribute to determine egg size in the south.     

Agricultural land use yields reduced foraging efficiency and unviable offspring in the wild bee Ceratina calcarata

1. Agricultural intensification generally leads to large‐scale habitat changes marked by decreasing availability of nesting sites and flower resources for pollinators. However, little is known about how such changes impact wild bee maternal body size and foraging effort and, more importantly, whether there is a subsequent effect on their offspring. 2. Nests were collected from the common eastern North American stem nesting bee, Ceratina calcarata, across three land management types: (i) intensely managed conventional farms; (ii) moderately disturbed organic farmland; and (iii) least managed roadsides. The study assessed the effects of land use types on body size and wing wear (a proxy for foraging effort) of maternal bees, and on their offspring in terms of clutch size, survival, sex ratio and body size. 3. Findings revealed that more brood reached pupal stages from nests collected in conventional farmlands. This was due to the total lack of parasites, possibly because the host density is below the threshold that can support a brood parasite population in intensively farmed landscapes. A positive association between maternal bee size and clutch size was only found in least managed roadsides, while, in both farm types, body sizes for daughters and sons were smaller, barely reaching the predicted overwintering threshold. 4. The results suggest that the effects of intensified agricultural land use will be more pronounced in bee offspring, potentially leading to decreased fitness for subsequent generations. This implies far‐reaching consequences for agricultural pollination services and declines in wild bee populations.     

Landscape composition and configuration in the central highlands of Ethiopia

Landscape dynamics are common phenomenon in the human‐dominated environments whereby it can be observed that the composition and configuration between landscape elements change over time. This dynamism brings about habitat loss and fragmentation that can greatly alter ecosystem services at patch, class, and landscape levels. We conducted a study to examine composition and configuration of forested landscape in the central highlands of Ethiopia using satellite images of over a period of four decades, and FRAGSTAT raster dataset was used to analyze fragmentation. Our result showed five land use/land cover (LULC) types in the study area. Cultivated land and settlement land increased at the expense of forestland, shrubland, and grassland. Fragmentation analysis showed the number of patches increased for all LULC types, indicating the level of fragmentation and interspersion. Juxtaposition increased for shrubland, grassland, and cultivated lands and decreased for settlement and forestland resulting in the fragmentation and isolation of patches. The study of LULC along with fragmentation at the landscape level can help improve our understanding of the pace at which conversion of landscape elements is happening and the impacts on ecosystem services as studies of LULC are courser in nature and would not show how each land use is reducing in size, proximity and shape among other things that determine ecosystem services. Such type of studies in rural landscapes are very vital to consider appropriate land management policies for the landscape level by taking into account the interaction between each element for sustainable development. We recommend land managers, conservationists, and land owners for observing the roles of each patch in the matrix to maximize the benefits than focusing on a single element.     

Occurrence of an herbicide‐resistant plant trait in agricultural field margins

Agricultural environments allow study of evolutionary change in plants. An example of evolution within agroecological systems is the selection for resistance to the herbicide glyphosate within the weed, Conyza canadensis. Changes in survivorship and reproduction associated with the development of glyphosate resistance (GR) may impact fitness and influence the frequency of occurrence of the GR trait. We hypothesized that site characteristics and history would affect the occurrence of GR C. canadensis in field margins. We surveyed GR occurrence in field margins and asked whether there were correlations between GR occurrence and location, crop rotation, GR crop trait rotation, crop type, use of tillage, and the diversity of herbicides used. In a field experiment, we hypothesized that there would be no difference in fitness between GR and glyphosate‐susceptible (GS) plants. We asked whether there were differences in survivorship, phenology, reproduction, and herbivory between 2 GR and 2 GS populations of C. canadensis in agrestal and ruderal habitats. We found that geographic location was an important factor in the occurrence of GR C. canadensis in field margins. Although not consistently associated with either glyphosate resistance or glyphosate susceptibility, there were differences in phenology, survivorship, and herbivory among biotypes of C. canadensis. We found equal or greater fitness in GR biotypes, compared to GS biotypes, and GR plants were present in field margins. Field margins or ruderal habitats may provide refugia for GR C. canadensis, allowing reproduction and further selection to occur as seeds recolonize the agrestal habitat. Agricultural practices may select for ecological changes that feed back into the evolution of plants in ruderal habitats.     

Population and Harvest Dynamics of Midcontinent Sandhill Cranes

Sandhill cranes (Antigone canadensis) inhabiting the midcontinent of North America have been hunted since the 1960s under management goals of maintaining abundance, retaining geographic distribution, and maximizing sustainable harvest. Some biologists have raised concerns regarding harvest sustainability because sandhill cranes have lower reproductive rates than other game birds. We summarized demographic information in an age-structured matrix model to better understand population dynamics and harvest. Population indices and recovered harvest since the early 1980s suggest midcontinent sandhill cranes have experienced an average long-term annual growth of 0.9%; meanwhile, harvest has increased 1.8% annually. Adult survival and recruitment rates estimated from field data required modest adjustments (1–3%) so that model-derived growth rates matched growth estimated from a long-term survey (0.887 adult survival and 0.199 females/breeding female). Considering 0.9% long-term annual growth, sandhill cranes could be harvested at a rate of 6.6% if harvest was additive to natural mortality (assumed to be 0.05) or 11.3% if harvest mortality compensated for natural mortality. Life-history characteristics for long-lived organisms and demographic evidence suggested that hunter harvest was primarily additive. Differential harvest rates of segments of sandhill cranes in the midcontinent population derived from differential exposure to hunting suggested potentially unsustainable harvest for greater sandhill cranes (A. c. tabida) from 2 breeding segments. Overall, demographic evidence suggests that the harvest of sandhill cranes in the midcontinent population has been managed sustainably. Monitoring activities that reduce nuisance variation and estimate vital and harvest rates by subspecies would support continued management of sandhill cranes that are of interest to hunters and bird watchers. Published 2020. This article is a U.S. Government work and is in the public domain in the USA.     

Effects of habitat transitions on rainforest bird communities across an anthropogenic landscape mosaic

We compared bird community responses to the habitat transitions of rainforest‐to‐pasture conversion, consequent habitat fragmentation, and post‐agricultural regeneration, across a landscape mosaic of about 600 km² in the eastern Australian subtropics. Birds were surveyed in seven habitats: continuous mature rainforest; two size classes of mature rainforest fragment (4–21 ha and 1–3 ha); regrowth forest patches dominated by a non‐native tree (2–20 ha, 30–50 years old); two types of isolated mature trees in pasture; and treeless pasture, with six sites per habitat. We compared the avifauna among habitats and among sites, at the levels of species, functional guilds, and community‐wide. Community‐wide species richness and abundance of birds in pasture sites were about one‐fifth and one‐third, respectively, of their values in mature rainforest (irrespective of patch size). Many measured attributes changed progressively across a gradient of increased habitat simplification. Rainforest specialists became less common and less diverse with decreased habitat patch size and vegetation maturity. However, even rainforest fragments of 1–3 ha supported about half of these species. Forest generalist species were largely insensitive to patch size and successional stage. Few species reached their greatest abundance in either small rainforest fragments or regrowth. All pastures were dominated by bird species whose typical native habitats were grassland, wetland, and open eucalypt forest, while pasture trees modestly enhanced local bird communities. Overall, even small scattered patches of mature and regrowth forest contributed substantial bird diversity to local landscapes. Therefore, maximizing the aggregate rainforest area is a useful regional conservation strategy.     

Unpredictable offspring survivorship in the damselfly, Megaloprepus coerulatus, shapes parental behavior, constrains sexual selection, and challenges traditional fitness estimates

Evolutionary biologists typically assume that the number of eggs fertilized or developing embryos produced is correlated with an individual's fitness. Using microsatellite markers, we document for the first time estimates of realized fitness quantified as the number of offspring surviving to adulthood in an insect under field conditions. In a territorial damselfly whose males defend tree hole oviposition sites, patterns of offspring survivorship could not be anticipated by adults. Fewer than half of the parents contributing eggs to a larval habitat realized any reproductive success from their investment. The best fitness correlate was the span over which eggs in a clutch hatched. Among parents, female fecundity and male fertilization success were poor predictors of realized fitness. Although body size was correlated with female clutch size and male mating success, larger parents did not realize greater fitness than smaller ones. The uncoupling of traditional fitness surrogates from realized fitness provides strong empirical evidence that selection at the larval stage constrains selection on mated adults.     

Genomics meets applied ecology: Characterizing habitat quality for sloths in a tropical agroecosystem

Understanding how habitat quality in heterogeneous landscapes governs the distribution and fitness of individuals is a fundamental aspect of ecology. While mean individual fitness is generally considered a key to assessing habitat quality, a comprehensive understanding of habitat quality in heterogeneous landscapes requires estimates of dispersal rates among habitat types. The increasing accessibility of genomic approaches, combined with field‐based demographic methods, provides novel opportunities for incorporating dispersal estimation into assessments of habitat quality. In this study, we integrated genomic kinship approaches with field‐based estimates of fitness components and approximate Bayesian computation (ABC) procedures to estimate habitat‐specific dispersal rates and characterize habitat quality in two‐toed sloths (Choloepus hoffmanni) occurring in a Costa Rican agricultural ecosystem. Field‐based observations indicated that birth and survival rates were similar in a sparsely shaded cacao farm and adjacent cattle pasture–forest mosaic. Sloth density was threefold higher in pasture compared with cacao, whereas home range size and overlap were greater in cacao compared with pasture. Dispersal rates were similar between the two habitats, as estimated using ABC procedures applied to the spatial distribution of pairs of related individuals identified using 3,431 single nucleotide polymorphism and 11 microsatellite locus genotypes. Our results indicate that crops produced under a sparse overstorey can, in some cases, constitute lower‐quality habitat than pasture–forest mosaics for sloths, perhaps because of differences in food resources or predator communities. Finally, our study demonstrates that integrating field‐based demographic approaches with genomic methods can provide a powerful means for characterizing habitat quality for animal populations occurring in heterogeneous landscapes.     

Hydrological responses of a valley‐bottom wetland to land‐use/land‐cover change in a South African catchment: making a case for wetland restoration

Valley‐bottom wetlands are valuable assets as they provide many ecosystem services to mankind. Despite their value, valley‐bottom wetlands are often exploited and land‐use/land‐cover (LULC) change results in trade‐offs in ecosystem services. We coupled physically based hydrological modeling and spatial analysis to examine the effects of LULC change on water‐related ecosystem services in the Kromme catchment: an important water‐providing catchment for the city of Port Elizabeth. LULC scenarios were constructed to match 5 different decades in the last 50 years to explore the potential effects of restoring the catchment to different historic benchmarks. In the Kromme catchment, valley‐bottom wetlands have declined by 84%, driven by key LULC changes: an increase in irrigated land (307 ha) and invasion by alien trees (336 ha). If the wetlands were restored to the relatively pristine extent and condition of the 1950s, riverflow could increase by approximately 1.13 million m³/a, about 6% of the current supply to Port Elizabeth. Wetland restoration would also significantly improve the catchment's ability to absorb extreme rainfall events, decreasing flood damage. We conclude that in the face of the water scarcity in this region, all ecosystem services, particularly those related to water flow regulation, should be taken into account by decision makers in charge of land zonation. Zonation decisions should not continue to be made on the basis of provisioning ecosystem services alone (i.e. food provision or dam yield). We recommend prioritization of the preservation and restoration of valley‐bottom wetlands providing water‐related ecosystem services to settlements downstream.     

Population ecology and life history of the diurnal skink Morethia boulengeri in arid Australia

Summary The life history and population ecology of the skink Morethia boulengeri were studied from September 1985 to May 1987 in populations in a riverine woodland habitat and at an abandoned homestead in Kinchega National Park. The population dynamics and life histories of the two populations were remarkably similar. Yearly mortality (including emigration) ranged from 0.84–0.89. The yearly emigration rate was 0.01–0.03. Size-and body-condition-dependent mortality could be demonstrated for the population in riverine woodland. Average spring time densities were similar in both study sites but varied between years and ranged from 421-1823 individuals/ha. M. boulengeri females laid on average 2.8 eggs per clutch and usually produced three clutches per year. Egg mass was significantly correlated with female snout-vent-length, but relative clutch mass and egg size were not. All surviving juveniles reproduced for the first time in their first year. Some activity occurred throughout the year. Preferred body temperatures decreased in the cooler months. The data fit demographic models of life history evolution.     

Density effect on great tit (Parus major) clutch size intensifies in a polluted environment

Long-term data on a great tit (Parus major) population breeding in a metal-polluted zone around a copper–nickel smelter indicate that, against expectations, the clutch size of this species is decreasing even though metal emissions in the area have decreased considerably over the past two decades. Here, we document long-term population-level changes in the clutch size of P. major and explore if changes in population density, population numbers of competing species, timing of breeding, breeding habitat, or female age distribution can explain decreasing clutch sizes. Clutch size of P. major decreased by one egg in the polluted zone during the past 21 years, while there was no significant change in clutch size in the unpolluted reference zone over this time period. Density of P. major nests was similar in both environments but increased threefold during the study period in both areas (from 0.8 to 2.4 nest/ha). In the polluted zone, clutch size has decreased as a response to a considerable increase in population density, while a corresponding density change in the unpolluted zone did not have such an effect. The other factors studied did not explain the clutch size trend. Fledgling numbers in the polluted environment have been relatively low since the beginning of the study period, and they do not show a corresponding decrease to that noted for the clutch size over the same time period. Our study shows that responses of commonly measured life-history parameters to anthropogenic pollution depend on the structure of the breeding population. Interactions between pollution and intrinsic population characters should therefore be taken into account in environmental studies.     

Effects of variation in breeding habitat on Ring Ouzel Turdus torquatus productivity and chick condition

Capsule Territory habitat influenced clutch size and within-brood variability of chick condition in Ring Ouzel Turdus torquatus.

Aims To assess the relationship of Ring Ouzel productivity and chick condition with territory habitat, in order to improve understanding of the importance of breeding habitat for population change.

Methods Productivity and chick condition were recorded for Ring Ouzel pairs in a small area of upland Scotland and these were related to vegetation and physical characteristics for all breeding territories using General Linear Models.

Results We found that clutch size and variability of chick condition varied with Ring Ouzel breeding habitat.

Clutch size was related to variation in territory habitat, broadly increasing with territory grass, sedge and rush cover. The best-supported models for within-brood variability of chick condition included fledgling number and territory habitat, with chick condition broadly becoming more variable with territory bracken cover. Relationships between breeding habitat and brood size, fledgling number or mean chick condition were not supported by the data, although statistical power was low.

Conclusion Breeding habitat may be a driver of demographic rates of Ring Ouzel, with the effects of poor habitat being passed on indirectly through chick condition. The population-level importance of these effects is unclear, but this study highlights a possible link between recent observed habitat changes and first-year survival, the demographic parameter contributing most to variation in population growth rate in UK Ring Ouzels.     

Can birds count eggs in their nests?

Sensory mechanisms controlling avian clutch size have diversified into distinct types, according to the nature of the input that is used to disrupt the growth of ovarian follicles and hence halt egg‐laying. In an article on brood parasitism, Lyon (2003) claimed that female American Coots Fulica americana can reduce their clutch size on the basis of visual cues in response to eggs laid in their nests by other females; in this species, therefore, egg counting would be used to control clutch size. After a close examination of the physiological determination of clutch size in American Coots, I show that seven of 17 parasitized clutches were smaller than the range controlled through the mechanism using an input to disrupt follicular growth (7–10 eggs per clutch). My reanalysis suggests that American Coots are incapable of adjusting clutch size via counting and re‐asserts that a species that can count eggs has yet to be found among birds that rely upon their own body heat for incubation.     

Comparing risk factors for population extinction

Extinction risk of natural populations of animals and plants is enhanced by many different processes, including habitat size reduction and toxic chemical exposure. We develop a method to evaluate different risk factors in terms of the decrease in the mean extinction time. We choose a population model with logistic growth, environmental and demographic stochasticities with three parameters (intrinsic growth rate r, carrying capacity K, and environmental noise sigma(2)(e)). The reduction in the habitat size decreases carrying capacity K only, whilst toxic chemical exposure decreases survivorship (or fertility) and in effect reduces both r and K. We derived a formula for the reduction in habitat size that decrease the mean extinction time by the same magnitude as a given level of toxic chemical exposure. In a large population (large K) or in a slowly growing population (small r), a small decrease in survivorship can cause the extinction risk increase corresponding to a significant reduction in the habitat size. This conclusion depends also on the nonlinearity of dose-effect relationship. To illustrate the method, we analyse a freshwater fish, Japanese crucian carp (Carassius auratus subsp.) in Lake Biwa.     

The reproductive success of sandhill cranes in midwestern landscapes

A number of wildlife species have recovered from the brink of extinction to flourish and, in some cases, even become a commonly recognized urban species (e.g., Canada goose [Branta canadensis]). Broadly extirpated from much of their historical range in North America, the sandhill crane (Antigone canadensis) demonstrated this potential for population recovery. The trajectory of the eastern population of greater sandhill cranes is remarkable—perhaps as many as 90,000 cranes now occur throughout the same Great Lakes states that reported only dozens of birds less than a century ago. However, understanding future population growth of the species remains uncertain because breeding birds are increasingly exposed to the pressures of urban sprawl and a changing agricultural landscape. From 2009 to 2014 we investigated the survival of sandhill crane nests and young up to 11 weeks of age (the point at which they are capable of flight) in the core of the eastern population's range in central Wisconsin and at its peripheral extent in a rapidly developing urban region of northeastern Illinois, USA. We located crane nests via systematic surveys on foot and from helicopters, we then radio-tagged the young and monitored them until they died or were capable to sustained flight. Overall, young were more likely to hatch from nests in Illinois (60%) than in central Wisconsin (46%), regardless of differences in land cover surrounding the nest site. In contrast, the survivorship of young was positively correlated with urban land cover in both regions but higher in central Wisconsin (54%) than in northeast Illinois (27%). Overall, the probability of producing young was greater in landscapes with more urban development, regardless of region. We suggest that differences in predator composition, predator behavior, and crane density between rural and urban areas is the primary reason for the difference in crane productivity. Higher recruitment of sandhill cranes using urban landscapes may allow cranes to echo the population trajectory of urban Canada geese. We anticipate that sandhill cranes will continue to use urban landscapes, and likely expand their geographic range as breeding pairs benefit from the increased survivorship of young in those landscapes. © The Wildlife Society, 2019     

Reproductive strategies and body shape in the European pond turtle (Emys orbicularis) from contrasting habitats in Italy

Comparisons within and among populations offer important insights into variation in life-history traits and possible adaptive patterns to environmental conditions. We present the results of observed differences in body size, body shape and patterns of reproduction in four separate populations of the European pond turtle Emys orbicularis in central and southern Italy – coastal ( n =3) and mountainous ( n =1) sites and pond ( n =2) and canal ( n= 2) habitats – to determine whether phenotypic plasticity affects reproductive output. Although we did not find any significant latitudinal variation in body size, we observed significant differences in body shape between canal (rounded body shape) and pond (elongated body shape) systems and smaller size with rounded shape in the mountainous population. Reproductive output is similar among populations (median=5 eggs per clutch), whereas reproductive investment (relative clutch mass to maternal body mass) is higher in the mountain population (one clutch per year) than in coastal populations (two clutches per year), suggesting differential trade-offs between geographic locality, elevation and habitat type. Turtle shell shape and geographic location together affect reproductive output in E. orbicularis in Italy.