•Research into local adaptation at fine spatial scales has received little attention.•We develop new quantitative definitions for microgeographic adaptation and the spatial scale of ...adaptation.•Mechanisms promoting microgeographic adaptation include strong natural selection and reductions in gene flow.•Microgeographic adaptation can fundamentally alter understanding of ecological and evolutionary dynamics.•New frontiers are needed in spatial evolutionary research, particularly the lower spatial bounds of local adaptation.
Local adaptation has been a major focus of evolutionary ecologists working across diverse systems for decades. However, little of this research has explored variation at microgeographic scales because it has often been assumed that high rates of gene flow will prevent adaptive divergence at fine spatial scales. Here, we establish a quantitative definition of microgeographic adaptation based on Wright's dispersal neighborhood that standardizes dispersal abilities, enabling this measure to be compared across species. We use this definition to evaluate growing evidence of evolutionary divergence at fine spatial scales. We identify the main mechanisms known to facilitate this adaptation and highlight illustrative examples of microgeographic evolution in nature. Collectively, this evidence requires that we revisit our understanding of the spatial scale of adaptation and consider how microgeographic adaptation and its driving mechanisms can fundamentally alter ecological and evolutionary dynamics in nature.
Biotic Multipliers of Climate Change Zarnetske, Phoebe L.; Skelly, David K.; Urban, Mark C.
Science (American Association for the Advancement of Science),
06/2012, Letnik:
336, Številka:
6088
Journal Article
Recenzirano
A focus on species interactions may improve predictions of the effects of climate change on ecosystems.
Many species face uncertain fates under climate change. Some will persist by shifting their ...range or adapting to local conditions, whereas others will be lost to extinction. Efforts to lessen the impacts of climate change on biodiversity depend on accurate forecasts. Most studies aiming to identify likely winners and losers consider species one at a time with a “climate envelope” approach that correlates species' occurrences with climatic and environmental variables. Using this method, researchers have predicted that by 2050, 15 to 37% of species will be faced with extinction (
1
). But which species are most likely to be under threat? And how will their loss affect the broader ecological community?
We need accurate predictions about how climate change will alter species distributions and abundances around the world. Most predictions assume simplistic dispersal scenarios and ignore biotic ...interactions. We argue for incorporating the complexities of dispersal and species interactions. Range expansions depend not just on mean dispersal, but also on the shape of the dispersal kernel and the population's growth rate. We show how models using species‐specific dispersal can produce more accurate predictions than models applying all‐or‐nothing dispersal scenarios. Models that additionally include species interactions can generate distinct outcomes. For example, species interactions can slow climate tracking and produce more extinctions than models assuming no interactions. We conclude that (1) just knowing mean dispersal is insufficient to predict biotic responses to climate change, and (2) considering interspecific dispersal variation and species interactions jointly will be necessary to anticipate future changes to biological diversity. We advocate for collecting key information on interspecific dispersal differences and strong biotic interactions so that we can build the more robust predictive models that will be necessary to inform conservation efforts as climates continue to change.
To predict the spread of invasive species, we need to understand the mechanisms that underlie their range expansion. Assuming random diffusion through homogeneous environments, invasions are expected ...to progress at a constant rate. However, environmental heterogeneity is expected to alter diffusion rates, especially by slowing invasions as populations encounter suboptimal environmental conditions. Here, we examine how environmental and landscape factors affect the local invasion speeds of cane toads (ChaunusBufomarinus) in Australia. Using high‐resolution cane toad data, we demonstrate heterogeneous regional invasion dynamics that include both decelerating and accelerating range expansions. Toad invasion speed increased in regions characterized by high temperatures, heterogeneous topography, low elevations, dense road networks, and high patch connectivity. Regional increases in the toad invasion rate might be caused by environmental conditions that facilitate toad reproduction and movement, by the evolution of long‐distance dispersal ability, or by some combination of these factors. In any case, theoretical predictions that neglect environmental influences on dispersal at multiple spatial scales may prove to be inaccurate. Early predictions of cane toad range expansion rates that assumed constant diffusion across homogeneous landscapes already have been proved wrong. Future attempts to predict range dynamics for invasive species should consider heterogeneity in (1) the environmental factors that determine dispersal rates and (2) the mobility of invasive populations because dispersal‐relevant traits can evolve in exotic habitats. As an invasive species spreads, it is likely to encounter conditions that influence dispersal rates via one or both of these mechanisms.
Most animals have complex life cycles including metamorphosis or other discrete life stage transitions, during which individuals may be particularly vulnerable to environmental stressors. With ...climate change, individuals will be exposed to increasing thermal and hydrologic variability during metamorphosis, which may affect survival and performance through physiological, behavioral, and ecological mechanisms. Furthermore, because metamorphosis entails changes in traits and vital rates, it is likely to play an important role in how populations respond to increasing climate variability. To identify mechanisms underlying population responses and associated trait and life history evolution, we need new approaches to estimating changes in individual traits and performance throughout metamorphosis, and we need to integrate metamorphosis as an explicit life stage in analytical models.
During metamorphosis and other discrete transitions between life stages, many animals are vulnerable and depend on environmental stability.As climates continue to change, increasing thermal and hydrologic variability may pose particular risks to metamorphic species, but we lack empirical and analytical resources for assessing these risks.Many aspects of metamorphosis are sensitive to environmental conditions, including timing and duration, extent of developmental change, and energy costs. Consequently, relative to effects on pre- and postmetamorphic stages, climate variability may have disproportionately strong effects on the traits, fitness, and survival of metamorphosing individuals.In turn, proximate effects of climate variability during metamorphosis may influence population dynamics and life history evolution by imposing trait and vital rate trade-offs with pre- and postmetamorphic life stages.
Research on endocrine disruption in frog populations, such as shifts in sex ratios and feminization of males, has predominantly focused on agricultural pesticides. Recent evidence suggests that ...suburban landscapes harbor amphibian populations exhibiting similar levels of endocrine disruption; however the endocrine disrupting chemical (EDC) sources are unknown. Here, we show that sex ratios of metamorphosing frogs become increasingly female-dominated along a suburbanization gradient. We further show that suburban ponds are frequently contaminated by the classical estrogen estrone and a variety of EDCs produced by plants (phytoestrogens), and that the diversity of organic EDCs is correlated with the extent of developed land use and cultivated lawn and gardens around a pond. Our work also raises the possibility that trace-element contamination associated with human land use around suburban ponds may be contributing to the estrogenic load within suburban freshwaters and constitutes another source of estrogenic exposure for wildlife. These data suggest novel, unexplored pathways of EDC contamination in human-altered environments. In particular, we propose that vegetation changes associated with suburban neighborhoods (e.g., from forests to lawns and ornamental plants) increase the distribution of phytoestrogens in surface waters. The result of frog sex ratios varying as a function of human land use implicates a role for environmental modulation of sexual differentiation in amphibians, which are assumed to only have genetic sex determination. Overall, we show that endocrine disruption is widespread in suburban frog populations and that the causes are likely diverse.
The extent to which sex reversal is associated with transitions in sex determining systems (XX-XY, ZZ-ZW, etc.) or abnormal sexual differentiation is predominantly unexplored in amphibians. This is ...in large part because most amphibian taxa have homomorphic sex chromosomes, which has traditionally made it challenging to identify discordance between phenotypic and genetic sex in amphibians, despite all amphibians having a genetic component to sex determination. Recent advances in molecular techniques such as genome complexity reduction and high throughput sequencing present a valuable avenue for furthering our understanding of sex determination in amphibians and other taxa with homomorphic sex chromosomes like many fish and reptiles.
We use DArTseq as a novel approach to identify sex-linked markers in the North American green frog (Rana clamitans melanota) using lab-reared tadpoles as well as wild-caught adults from seven ponds either in undeveloped, forested habitats or suburban ponds known to be subject to contamination by anthropogenic chemicals. The DArTseq methodology identified 13 sex-linked SNP loci and eight presence-absence loci associated with males, indicating an XX-XY system. Both alleles from a single locus show partial high sequence homology to Dmrt1, a gene linked to sex determination and differentiation throughout Metazoa. Two other loci have sequence similarities to regions of the chimpanzee and human X-chromosome as well as the chicken Z-chromosome. Several loci also show geographic variation in sex-linkage, possibly indicating sex chromosome recombination. While all loci are statistically sex-linked, they show varying degrees of female heterozygosity and male homozygosity, providing further evidence that some markers are on regions of the sex chromosomes undergoing higher rates of recombination and therefore further apart from the putative sex determining locus.
The ease of the DArTseq platform provides a useful avenue for future research on sex reversal and sex chromosome evolution in vertebrates, particularly for non-model species with homomorphic or cryptic or nascent sex chromosomes.
Predation risk causes prey to react in numerous ways, from life history changes to shifts in habitat. These responses give some insight into how different types of predators affect prey, but prey ...responses are often not comparable across taxa and experimental systems. Metabolism is a ubiquitous trait among living organisms, which offers a way to examine predator effects and create generalizable outcomes. We examined metabolic responses of terrestrial and aquatic prey from three antipredator functional groups under varied contexts of predator cues. We found that constitutively defended prey did not exhibit metabolic responses to any type of predator cues, while deimatic and freeze‐flight prey exhibited metabolic responses that were dependent on both the cue type and predator hunting mode. Consistent with previous studies on nonconsumptive effects, we also found that ambush predators elicited a metabolic response while active predators did not. We propose that future work on this topic should continue to take a metabolic approach as a unified, scalable response variable to the sensory ecology of nonconsumptive effects, while identifying additional systems that can evaluate more fully both predator hunting mode and prey antipredator defenses.
Large-scale field patterns are a fundamental source of inferences on processes responsible for variation in species richness among habitats. We examined species richness of larval amphibian ...communities in 37 ponds over seven years on the Univ. of Michigan's E. S. George Reserve. Ordination of the community incidence matrix indicated a strong major axis of variation in species associations that was correlated with pond hydroperiod, surface area and forest canopy cover. Communities were significantly nested with those species found in ponds with high canopy cover, small area and short hydroperiod being nested subsets of those found in ponds with contrasting characteristics. Presence of fish had strong negative effects on species richness; relaxation of this effect also was apparent when fish were extirpated from ponds by drought. We employed a model selection analysis to identify the most appropriate statistical model for predicting the long-term average species richness of these ponds from local abiotic and biotic (predator and competitor density) factors. A model including only the abiotic factors was overwhelmingly superior for the anurans; hierarchical partitioning indicated that area and canopy cover alone accounted for over 70% of the independent effects of predictor variables. The global model including both abiotic and biotic factors was the best supported model for the caudates, and correspondingly hierarchical partitioning suggested that area, hydroperiod, invertebrate predators and caudate biomass all accounted for 9-16% of the independent effects. Overall, biotic factors accounted for much less of the variation in species richness than abiotic factors. The patterns in larger, open-canopy ponds provided little evidence of competitive effects on species richness, though there were patterns consistent with competitive effects in small, closed-canopy ponds. The unusual temporal and spatial extent of these data enabled us to critically evaluate ideas regarding patterns in larval amphibian communities, and the effects of area, disturbance (hydroperiod) and productivity (canopy cover) on species richness of these communities. These results have important implications to the conservation of amphibian species richness in freshwater wetlands, which are among the most threatened ecosystems worldwide.
Estimating species relative abundances from museum records Gotelli, Nicholas J.; Booher, Douglas B.; Urban, Mark C. ...
Methods in ecology and evolution,
February 2023, 2023-02-00, 20230201, 2023-02-01, Letnik:
14, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Dated, geo‐referenced museum specimens are a rich data source for reconstructing species' distribution and abundance patterns. However, museum records are potentially biased towards ...over‐representation of rare species, and it is unclear whether museum records can be used to estimate relative abundance in the field.
We assembled 17 coupled field and museum datasets to quantitatively compare relative abundance estimates with the Dirichlet distribution. Collectively, these datasets comprise 73,039 museum records and 1,405,316 field observations of 2,240 species.
Although museum records of rare species overestimated relative abundance by 1‐fold to over 100‐fold (median study = 9.0), the relative abundance of species estimated from museum occurrence records was strongly correlated with relative abundance estimated from standardized field surveys (r2 range of 0.10–0.91, median study = 0.43).
These analyses provide a justification for estimating species relative abundance with carefully curated museum occurrence records, which may allow for the detection of temporal or spatial shifts in the rank ordering of common and rare species.
Resumen
Los especímenes de museo fechados y georreferenciados son una rica fuente de datos para reconstruir los patrones de distribución y abundancia de las especies. Sin embargo, los registros de los museos están potencialmente sesgados hacia la sobrerrepresentación de especies raras, y no está claro si estos registros pueden utilizarse para estimar la abundancia relativa en el campo.
Se reunieron 17 conjuntos de datos acoplados de campo y de museo para comparar cuantitativamente las estimaciones de abundancia relativa con la distribución de Dirichlet. Colectivamente, estos conjuntos de datos comprenden 73.039 registros de museo y 1.405.316 observaciones de campo para 2.240 especies.
Aunque los registros de museo de especies raras sobreestimaron la abundancia relativa desde 1 hasta más de 100 veces (mediana del estudio = 9,0), la abundancia relativa de las especies que se estimada a partir de los registros de ocurrencia de los museos mostró una fuerte correlación con la abundancia relativa estimada a partir de los estudios de campo estandarizados (rango r2 de 0,10 a 0,91, mediana del estudio = 0,43).
Estos análisis justifican la estimación de la abundancia relativa de las especies a partir de los registros de ocurrencia de los museos, lo que permitiría la detección de cambios temporales o espaciales en el rango de ordenamiento de las especies comunes y raras.
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