scholarly journals May the (selective) force be with you: Spatial sorting and natural selection exert opposing forces on limb length in an invasive amphibian

2019 ◽  
Vol 32 (9) ◽  
pp. 994-1001 ◽  
Author(s):  
Gregory S. Clarke ◽  
Richard Shine ◽  
Benjamin L. Phillips
Keyword(s):  
Natural Selection ◽  
Limb Length ◽  
Selective Force ◽  
Spatial Sorting

scholarly journals Repeated modification of early limb morphogenesis programmes underlies the convergence of relative limb length in Anolis lizards

2011 ◽  
Vol 279 (1729) ◽  
pp. 739-748 ◽  
Author(s):  
Thomas J. Sanger ◽  
Liam J. Revell ◽  
Jeremy J. Gibson-Brown ◽  
Jonathan B. Losos
Keyword(s):  
Natural Selection ◽  
Developmental Trajectories ◽  
Limb Length ◽  
Long Bone ◽  
Length Variation ◽  
Developmental Processes ◽  
Independent Evolution ◽  
Limb Morphogenesis ◽  
Habitat Specialists ◽  
Phenotypic Convergence

The independent evolution of similar morphologies has long been a subject of considerable interest to biologists. Does phenotypic convergence reflect the primacy of natural selection, or does development set the course of evolution by channelling variation in certain directions? Here, we examine the ontogenetic origins of relative limb length variation among Anolis lizard habitat specialists to address whether convergent phenotypes have arisen through convergent developmental trajectories. Despite the numerous developmental processes that could potentially contribute to variation in adult limb length, our analyses reveal that, in Anolis lizards, such variation is repeatedly the result of changes occurring very early in development, prior to formation of the cartilaginous long bone anlagen.

scholarly journals It is lonely at the front: contrasting evolutionary trajectories in male and female invaders

2016 ◽  
Vol 3 (12) ◽  
pp. 160687 ◽  
Author(s):  
Cameron M. Hudson ◽  
Gregory P. Brown ◽  
Richard Shine
Keyword(s):  
Sexual Dimorphism ◽  
Common Garden ◽  
Limb Length ◽  
Phenotypic Traits ◽  
Evolutionary Changes ◽  
Spatial Sorting ◽  
Significant Heritability ◽  
Selective Forces ◽  
Major Shift ◽  
Sex Disparity

Invasive species often exhibit rapid evolutionary changes, and can provide powerful insights into the selective forces shaping phenotypic traits that influence dispersal rates and/or sexual interactions. Invasions also may modify sexual dimorphism. We measured relative lengths of forelimbs and hindlimbs of more than 3000 field-caught adult cane toads ( Rhinella marina ) from 67 sites in Hawai'i and Australia (1–80 years post-colonization), along with 489 captive-bred individuals from multiple Australian sites raised in a ‘common garden’ (to examine heritability and reduce environmental influences on morphology). As cane toads spread from east to west across Australia, the ancestral condition (long limbs, especially in males) was modified. Limb length relative to body size was first reduced (perhaps owing to natural selection on locomotor ability), but then increased again (perhaps owing to spatial sorting) in the invasion vanguard. In contrast, the sex disparity in relative limb length has progressively decreased during the toads' Australian invasion. Offspring reared in a common environment exhibited similar geographical divergences in morphology as did wild-caught animals, suggesting a genetic basis to the changes. Limb dimensions showed significant heritability (2–17%), consistent with the possibility of an evolved response. Cane toad populations thus have undergone a major shift in sexual dimorphism in relative limb lengths during their brief (81 years) spread through tropical Australia.

scholarly journals Does the variance of incubation temperatures always constitute a significant selective force for origin of reptilian viviparity?

2012 ◽  
Vol 58 (6) ◽  
pp. 812-819 ◽  
Author(s):  
Hong Li ◽  
Zheng Wang ◽  
Ce Chen ◽  
Xiang Ji
Keyword(s):  
Hind Limb ◽  
Hatching Success ◽  
Incubation Temperature ◽  
Tail Length ◽  
Thermal Fluctuations ◽  
Limb Length ◽  
Selective Force ◽  
Sprint Speed ◽  
The Mean ◽  
Incubation Temperatures

Abstract To test the hypothesis that the variance of incubation temperature may have constituted a significant selective force for reptilian viviparity, we incubated eggs of the slender forest skink Scincella modesta in five thermally different natural nests and at two constant temperatures (18 °C and 21 °C). Our manipulation of incubation temperature had significant effects on incubation length and several hatchling traits (snout-vent length, tail length, fore-limb length, and sprint speed), but not on hatching success and other hatchling traits examined (body mass, head size, and hind-limb length). Incubation length was nonlinearly sensitive to temperature, but it was not correlated with the thermal variance when holding the thermal mean constant. The 18 °C treatment not only produced smaller sized hatchlings but also resulted in decreased sprint speed. Eggs in the nest with the greatest proportion of temperatures higher than 28 °C also produced smaller sized hatchlings. None of the hatchling traits examined was affected by the thermal variance. Thermal fluctuations did result in longer incubation times, but females would benefit little from maintaining stable body temperatures or selecting thermally stable nests in terms of the reduced incubation length. Our data show that the mean rather than the variance of temperatures has a key role in influencing incubation length and hatchling phenotypes, and thus do not support the hypothesis tested.

scholarly journals Reply to Lee: Spatial sorting, assortative mating, and natural selection

2011 ◽  
Vol 108 (31) ◽  
pp. E348-E348 ◽  
Author(s):  
R. Shine ◽  
G. P. Brown ◽  
B. L. Phillips
Keyword(s):  
Natural Selection ◽  
Assortative Mating ◽  
Spatial Sorting

scholarly journals Evolution of dispersal can rescue populations from expansion load

2018 ◽  
Author(s):  
Stephan Peischl ◽  
Kimberly J. Gilbert
Keyword(s):  
Natural Selection ◽  
Genetic Drift ◽  
Evolutionary Biology ◽  
Empirical Work ◽  
Leading Edge ◽  
Slowing Down ◽  
Spatial Sorting ◽  
Mean Fitness ◽  
Expansion Load ◽  
Probability Of Fixation

AbstractUnderstanding the causes and consequences of range expansions or range shifts has a long history in evolutionary biology. Recent theoretical, experimental, and empirical work has identified two particularly interesting phenomena in the context of species range expansions: (i) gene surfing and the relaxation of natural selection, and (ii) spatial sorting. The former can lead to an accumulation of deleterious mutations at range edges, causing an expansion load and slowing down expansion. The latter can create gradients in dispersal-related traits along the expansion axis and cause an acceleration of expansion. We present a theoretical framework that treats spatial sorting and gene surfing as spatial versions of natural selection and genetic drift, respectively. This model allows us to study analytically how gene surfing and spatial sorting interact, and to derive the probability of fixation of pleiotropic mutations at the expansion front. We use our results to predict the co-evolution of mean fitness and dispersal rates, taking into account the effects of random genetic drift, natural selection and spatial sorting, as well as correlations between fitnessand dispersal-related traits. We identify a “rescue effect” of spatial sorting, where the evolution of higher dispersal rates at the leading edge rescues the population from incurring expansion load.

scholarly journals Spatial sorting as the spatial analogue of natural selection

2017 ◽  
Author(s):  
Ben L. Phillips ◽  
T. Alex Perkins
Keyword(s):  
Natural Selection ◽  
Habitat Quality ◽  
Rapid Evolution ◽  
General Mechanism ◽  
Dispersal Ability ◽  
Spatial Sorting ◽  
Temporal Aspects ◽  
Varying Environments ◽  
High Level ◽  
Dispersal Evolution

AbstractIn most systems, dispersal occurs despite clear fitness costs to dispersing individuals. Theory posits that spatial heterogeneity in habitat quality pushes dispersal rates to evolve towards zero, while temporal heterogeneity in habitat quality favours non-zero dispersal rates. One aspect of dispersal evolution that has received a great deal of recent attention is a process known as spatial sorting, which has been referred to as a “shy younger sibling” of natural selection. More precisely, spatial sorting is the process whereby variation in dispersal ability is sorted along density clines and will, in nature, often be a transient phenomenon. Despite this transience, spatial sorting is likely a general mechanism behind non-zero dispersal in spatiotemporally varying environments. While generally transient, spatial sorting is persistent on invasion fronts, where its effect cannot be ignored, causing rapid evolution of traits related to dispersal. Spatial sorting is described in several elegant models, yet these models require a high level of mathematical sophistication and are not accessible to most evolutionary biologists or their students. Here, we frame spatial sorting in terms of the classic haploid and diploid models of natural selection. We show that, on an invasion front, spatial sorting can be conceptualized precisely as selection operating through space rather than (as with natural selection) time, and that genotypes can be viewed as having both spatial and temporal aspects of fitness. The resultant model is strikingly similar to classic models of natural selection. This similarity renders the model easy to understand (and to teach), but also suggests that many established theoretical results around natural selection could apply equally to spatial sorting.

scholarly journals Algebraic theorem of selection by spatial sorting

2021 ◽  
Author(s):  
Nikunj Goel
Keyword(s):  
Natural Selection ◽  
Global Change ◽  
Mathematical Theory ◽  
Range Shifts ◽  
Lifetime Reproductive Success ◽  
Heritable Variation ◽  
Evolutionary Patterns ◽  
Spatial Sorting ◽  
Natural Selection Theory

Heritable variation in traits that enhance dispersal rates can accumulate at population margins by spatial sorting. This mechanism of selection differs from natural selection as evolutionary change can ensue even in the absence of differential lifetime reproductive success. Although evidence suggests that populations are rapidly evolving at margins due to global change pressures, such as invasions and range shifts, we lack a mathematical theory of spatial sorting to understand these evolutionary patterns. To this end, we present an algebraic theorem, or the sorting theorem, to elucidate the nature of selection at margins, which can, in turn, facilitate axiomatic development of spatial sorting theory. The role of the sorting theorem in guiding research in this context is analogous to that of Price's theorem in natural selection theory.

scholarly journals Spatial sorting as the spatial analogue of natural selection

2019 ◽  
Vol 12 (2) ◽  
pp. 155-163 ◽  
Author(s):  
Ben L. Phillips ◽  
T. Alex Perkins
Keyword(s):  
Natural Selection ◽  
Spatial Sorting

scholarly journals Changes in selection pressure can facilitate hybridization during biological invasion in a Cuban lizard

2021 ◽  
Vol 118 (42) ◽  
pp. e2108638118
Author(s):  
Dan G. Bock ◽  
Simon Baeckens ◽  
Jessica N. Pita-Aquino ◽  
Zachary A. Chejanovski ◽  
Sozos N. Michaelides ◽  
...  
Keyword(s):  
Natural Selection ◽  
Large Scale ◽  
Limb Length ◽  
Native Range ◽  
Evolutionary Mechanisms ◽  
Invasive Range ◽  
Temporal Sampling ◽  
Contemporary Gene Flow ◽  
Brown Anole ◽  
Show Evidence

Hybridization is among the evolutionary mechanisms most frequently hypothesized to drive the success of invasive species, in part because hybrids are common in invasive populations. One explanation for this pattern is that biological invasions coincide with a change in selection pressures that limit hybridization in the native range. To investigate this possibility, we studied the introduction of the brown anole (Anolis sagrei) in the southeastern United States. We find that native populations are highly genetically structured. In contrast, all invasive populations show evidence of hybridization among native-range lineages. Temporal sampling in the invasive range spanning 15 y showed that invasive genetic structure has stabilized, indicating that large-scale contemporary gene flow is limited among invasive populations and that hybrid ancestry is maintained. Additionally, our results are consistent with hybrid persistence in invasive populations resulting from changes in natural selection that occurred during invasion. Specifically, we identify a large-effect X chromosome locus associated with variation in limb length, a well-known adaptive trait in anoles, and show that this locus is often under selection in the native range, but rarely so in the invasive range. Moreover, we find that the effect size of alleles at this locus on limb length is much reduced in hybrids among divergent lineages, consistent with epistatic interactions. Thus, in the native range, epistasis manifested in hybrids can strengthen extrinsic postmating isolation. Together, our findings show how a change in natural selection can contribute to an increase in hybridization in invasive populations.

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