Rates of population differentiation and speciation are decoupled in sea snakes

Comparative phylogeography can inform many macroevolutionary questions, such as whether species diversification is limited by rates of geographical population differentiation. We examined the link between population genetic structure and species diversification in the fully aquatic sea snakes (Hydrophiinae) by comparing mitochondrial phylogeography across northern Australia in 16 species from two closely related clades that show contrasting diversification dynamics. Contrary to expectations from theory and several empirical studies, our results show that, at the geographical scale studied here, rates of population differentiation and speciation are not positively linked in sea snakes. The eight species sampled from the rapidly speciating Hydrophis clade have weak population differentiation that lacks geographical structure. By contrast, all eight sampled Aipysurus–Emydocephalus species show clear geographical patterns and many deep intraspecific splits, but have threefold slower speciation rates. Alternative factors, such as ecological specialization, species duration and geographical range size, may underlie rapid speciation in sea snakes.

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Investigating the reliability of molecular estimates of evolutionary time when substitution rates and speciation rates vary

10.1101/2021.06.27.450013 ◽

2021 ◽

Author(s):

Andrew M Ritchie ◽

Xia Hua ◽

Lindell Bromham

Keyword(s):

Dna Sequences ◽

Empirical Studies ◽

Divergence Time ◽

Molecular Dating ◽

Rate Variation ◽

Substitution Rates ◽

Molecular Change ◽

Dna Evidence ◽

Dating Methods ◽

Speciation Rates

Background An accurate timescale of evolutionary history is essential to testing hypotheses about the influence of historical events and processes, and the timescale for evolution is increasingly derived from analysis of DNA sequences. But variation in the rate of molecular evolution complicates the inference of time from DNA. Evidence is growing for numerous factors, such as life history and habitat, that are linked both to the molecular processes of mutation and fixation and to rates of macroevolutionary diversification. However, the most widely used models of molecular rate variation, such as the uncorrelated and autocorrelated lognormal clocks, rely on idealised models of rate variation and molecular dating methods are rarely tested against complex models of rate change. One relationship that is not accounted for in molecular dating is the potential for interaction between molecular substitution rates and speciation, a relationship that has been supported by empirical studies in a growing number of taxa. If these relationships are as widespread as evidence indicates, they may have a significant influence on molecular dates. Results We simulate phylogenies and molecular sequences under three different realistic rate variation models - one in which speciation rates and substitution rates both vary but are unlinked, one in which they covary continuously and one punctuated model in which molecular change is concentrated in speciation events, using empirical case studies to parameterise realistic simulations. We test two commonly used "relaxed clock" molecular dating methods against these realistic simulations to explore the degree of error in molecular dates under each model. We find average divergence time inference errors ranging from 12% of node age for the unlinked model when reconstructed under an uncorrelated rate prior, to up to 93% when punctuated simulations are reconstructed under an autocorrelated prior. Conclusions We demonstrate the potential for substantial errors in molecular dates when both speciation rates and substitution rates vary between lineages. This study highlights the need for tests of molecular dating methods against realistic models of rate variation generated from empirical parameters and known relationships.

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Positive association between population genetic differentiation and speciation rates in New World birds

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1617397114 ◽

2017 ◽

Vol 114 (24) ◽

pp. 6328-6333 ◽

Cited By ~ 43

Author(s):

Michael G. Harvey ◽

Glenn F. Seeholzer ◽

Brian Tilston Smith ◽

Daniel L. Rabosky ◽

Andrés M. Cuervo ◽

...

Keyword(s):

Population Differentiation ◽

New World ◽

Bird Species ◽

Positive Association ◽

Tropical Species ◽

Implicit Assumption ◽

Speciation Rate ◽

Population Genetic Differentiation ◽

Evolutionary Diversification ◽

Speciation Rates

An implicit assumption of speciation biology is that population differentiation is an important stage of evolutionary diversification, but its significance as a rate-limiting control on phylogenetic speciation dynamics remains largely untested. If population differentiation within a species is related to its speciation rate over evolutionary time, the causes of differentiation could also be driving dynamics of organismal diversity across time and space. Alternatively, geographic variants might be short-lived entities with rates of formation that are unlinked to speciation rates, in which case the causes of differentiation would have only ephemeral impacts. By pairing population genetics datasets from 173 New World bird species (>17,000 individuals) with phylogenetic estimates of speciation rate, we show that the population differentiation rates within species are positively correlated with their speciation rates over long timescales. Although population differentiation rate explains relatively little of the variation in speciation rate among lineages, the positive relationship between differentiation rate and speciation rate is robust to species-delimitation schemes and to alternative measures of both rates. Population differentiation occurs at least three times faster than speciation, which suggests that most populations are ephemeral. Speciation and population differentiation rates are more tightly linked in tropical species than in temperate species, consistent with a history of more stable diversification dynamics through time in the Tropics. Overall, our results suggest that the processes responsible for population differentiation are tied to those that underlie broad-scale patterns of diversity.

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Tracing geographical patterns of population differentiation in a widespread mangrove gastropod: genetic and geometric morphometrics surveys along the eastern African coast

Biological Journal of the Linnean Society ◽

10.1111/j.1095-8312.2012.01967.x ◽

2012 ◽

Vol 107 (3) ◽

pp. 647-663 ◽

Cited By ~ 13

Author(s):

Carolina Madeira ◽

Maria Judite Alves ◽

Natacha Mesquita ◽

Sara Ema Silva ◽

José Paula

Keyword(s):

Geometric Morphometrics ◽

Population Differentiation ◽

Geographical Patterns ◽

African Coast

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Ecological mechanisms explaining interactions within plant–hummingbird networks: morphological matching increases towards lower latitudes

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2019.2873 ◽

2020 ◽

Vol 287 (1922) ◽

pp. 20192873 ◽

Cited By ~ 7

Author(s):

Jesper Sonne ◽

Jeferson Vizentin-Bugoni ◽

Pietro K. Maruyama ◽

Andréa C. Araujo ◽

Edgar Chávez-González ◽

...

Keyword(s):

Low Temperature ◽

Environmental Gradients ◽

Modular Network ◽

Potential Explanation ◽

Geographical Patterns ◽

Resource Specialization ◽

Geographical Scale ◽

Species Abundances ◽

Ecological Mechanisms ◽

Temperature Seasonality

Interactions between species are influenced by different ecological mechanisms, such as morphological matching, phenological overlap and species abundances. How these mechanisms explain interaction frequencies across environmental gradients remains poorly understood. Consequently, we also know little about the mechanisms that drive the geographical patterns in network structure, such as complementary specialization and modularity. Here, we use data on morphologies, phenologies and abundances to explain interaction frequencies between hummingbirds and plants at a large geographical scale. For 24 quantitative networks sampled throughout the Americas, we found that the tendency of species to interact with morphologically matching partners contributed to specialized and modular network structures. Morphological matching best explained interaction frequencies in networks found closer to the equator and in areas with low-temperature seasonality. When comparing the three ecological mechanisms within networks, we found that both morphological matching and phenological overlap generally outperformed abundances in the explanation of interaction frequencies. Together, these findings provide insights into the ecological mechanisms that underlie geographical patterns in resource specialization. Notably, our results highlight morphological constraints on interactions as a potential explanation for increasing resource specialization towards lower latitudes.

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Trophic niche divergence among colour morphs that exhibit alternative mating tactics

Royal Society Open Science ◽

10.1098/rsos.150531 ◽

2016 ◽

Vol 3 (4) ◽

pp. 150531 ◽

Cited By ~ 14

Author(s):

Matthew S. Lattanzio ◽

Donald B. Miles

Keyword(s):

Alternative Hypothesis ◽

Reproductive Behaviour ◽

Trophic Niche ◽

Trophic Levels ◽

Alternative Mating Tactics ◽

Ecological Specialization ◽

Mating Tactics ◽

Habitat Variation ◽

Speciation Rates ◽

Colour Morphs

Discrete colour morphs associated with alternative mating tactics are assumed to be ecologically equivalent. Yet suites of behaviours linked with reproduction can also favour habitat segregation and exploitation of different prey among morphs. By contrast, trophic polymorphisms are usually attributed to morphs exhibiting habitat or prey selectivity. An alternative hypothesis is that habitat variation generates a trophic polymorphism driven by differences in morph reproductive behaviour, the spatial dispersion of morphs in a landscape and their exposure to different prey types. In this scenario, morphs are allowed to vary in habitat or diet selectivity (e.g. specialist or generalist) as they do in behaviour, rather than being assumed to exhibit equivalent levels of ecological specialization. We test this hypothesis using male Urosaurus ornatus lizards that exhibit a discrete dewlap colour polymorphism that reflects alternative mating tactics. We found blue morphs specialize on prey at higher trophic levels, yellow males display plasticity in trophic and morphological attributes and orange males are trophic generalists. Our results also demonstrate that morph diet differences are enhanced in resource-limited habitats. We conclude that discrete behavioural morphs may also diverge in morphology and trophic niche. Jointly, these processes may enhance speciation rates in colour polymorphic taxa.

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Trophic network structure emerges through antagonistic coevolution in temporally varying environments

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2011.0826 ◽

2011 ◽

Vol 279 (1727) ◽

pp. 299-308 ◽

Cited By ~ 25

Author(s):

Timothée Poisot ◽

Peter H. Thrall ◽

Michael E. Hochberg

Keyword(s):

Network Structure ◽

Environmental Variability ◽

Empirical Studies ◽

Single Species ◽

Theoretical Work ◽

Bipartite Network ◽

Ecological Specialization ◽

Natural Systems ◽

Trophic Network ◽

Varying Environments

Understanding the mechanisms underlying ecological specialization is central to our understanding of community ecology and evolution. Although theoretical work has investigated how variable environments may affect specialization in single species, little is known about how such variation impacts bipartite network structure in antagonistically coevolving systems. Here, we develop and analyse a general model of victim–enemy coevolution that explicitly includes resource and population dynamics. We investigate how temporal environmental heterogeneity affects the evolution of specialization and associated community structure. Environmental productivity influences victim investment in resistance, which will shape patterns of specialization through its regulating effect on enemy investment in infectivity. We also investigate the epidemiological consequences of environmental variability and show that enemy population density is maximized for intermediate lengths of productive seasons, which corresponds to situations where enemies can evolve higher infectivity than victims can evolve defence. We discuss our results in the light of empirical studies, and further highlight ways in which our model applies to a range of natural systems.

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Heterostyly accelerates diversification via reduced extinction in primroses

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2014.0075 ◽

2014 ◽

Vol 281 (1784) ◽

pp. 20140075 ◽

Cited By ~ 59

Author(s):

Jurriaan M. de Vos ◽

Colin E. Hughes ◽

Gerald M. Schneeweiss ◽

Brian R. Moore ◽

Elena Conti

Keyword(s):

Time Scales ◽

Sister Group ◽

Genetic Effects ◽

Evolutionary Time ◽

Species Diversification ◽

Sexual Systems ◽

Extinction Rates ◽

Angiosperm Diversification ◽

Speciation Rates ◽

Floral Syndrome

The exceptional species diversity of flowering plants, exceeding that of their sister group more than 250-fold, is especially evident in floral innovations, interactions with pollinators and sexual systems. Multiple theories, emphasizing flower–pollinator interactions, genetic effects of mating systems or high evolvability, predict that floral evolution profoundly affects angiosperm diversification. However, consequences for speciation and extinction dynamics remain poorly understood. Here, we investigate trajectories of species diversification focusing on heterostyly, a remarkable floral syndrome where outcrossing is enforced via cross-compatible floral morphs differing in placement of their respective sexual organs. Heterostyly evolved at least 20 times independently in angiosperms. Using Darwin's model for heterostyly, the primrose family, we show that heterostyly accelerates species diversification via decreasing extinction rates rather than increasing speciation rates, probably owing to avoidance of the negative genetic effects of selfing. However, impact of heterostyly appears to differ over short and long evolutionary time-scales: the accelerating effect of heterostyly on lineage diversification is manifest only over long evolutionary time-scales, whereas recent losses of heterostyly may prompt ephemeral bursts of speciation. Our results suggest that temporal or clade-specific conditions may ultimately determine the net effects of specific traits on patterns of species diversification.

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Business Micro-Location: Factors, Preferences and Indicators to Assess the Influence Factors

Management and Production Engineering Review ◽

10.2478/mper-2013-0013 ◽

2013 ◽

Vol 4 (2) ◽

pp. 25-36

Author(s):

Cornel Ghita ◽

Cezar Scarlat ◽

José Freitas Santos ◽

Antonio Correia de Barros

Keyword(s):

Empirical Studies ◽

Geographical Area ◽

Influence Factors ◽

Location Theory ◽

Geographical Information ◽

Location Factors ◽

Cross Sectional ◽

Geographical Scale ◽

Established Firms ◽

Sectional Analysis

Abstract The paper presents a study on business micro-location behaviour as well as corresponding factors of influence, conducted in two metropolitan areas, Bucharest-Ilfov (Romania) and Greater Porto (Portugal). By business micro-location we refer to a specific site such as a building or facility, accommodating a business within a small, compact geographical area (e.g. metropolitan area). At this geographical scale, the macroeconomic layer factors were excluded, applicable when discern between regions or countries. The factors derived from location theory and previous empirical studies were surveyed, completing a cross-sectional analysis in order to find out the specific weights of the location factors and preferences, by region and by industry. Based on already established firms’ feedback on location, the specific weights were granted by each industry to the main location factors, types of areas, and types of accommodation facilities. The authors also suggested a model to integrate these results into a Geographical Information System (GIS).

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Allochronic Divergence Driven by Spatial Asynchrony in Precipitation in Neotropical Frogs?

10.1101/2020.05.05.079210 ◽

2020 ◽

Author(s):

Carlos E. Guarnizo ◽

Paola Montoya ◽

Ignacio Quintero ◽

Carlos Daniel Cadena

Keyword(s):

Species Richness ◽

Genetic Divergence ◽

Meta Analysis ◽

Population Divergence ◽

Ecological Connectivity ◽

Geographical Patterns ◽

Geographic Barriers ◽

Precipitation Regimes ◽

Species Effect ◽

Speciation Rates

AbstractThe role of geographic barriers in promoting reproductive isolation across space is well understood. Isolation by the time of breeding, however, may also promote population divergence when populations reproduce asynchronically in space, even in the absence of geographic barriers. Few examples exist of divergence due to breeding allochrony, particularly in vertebrates. We tested whether in Neotropical frogs’ asynchrony in precipitation patterns promotes intraspecific genetic divergence, speciation, and regional accumulation of diversity. We assessed the relationship between spatial asynchrony in precipitation and genetic divergence controlling for ecological connectivity across 48 Neotropical frog species. In addition, we examined whether regions within which precipitation regimes are more asynchronous across space have higher species richness and have experienced greater speciation rates. Beyond a generalized expected effect of ecological connectivity on intraspecific genetic divergence, we found that asynchrony in precipitation is positively associated with genetic differentiation in 31% of the species tested, resulting in a significantly positive cross-species effect of asynchrony in precipitation on genetic divergence in a meta-analysis. However, the effect of asynchrony in precipitation on population divergence seems not to scale to macroevolutionary patterns because spatial asynchrony in precipitation was not associated with geographical patterns of species richness or speciation rates. Our results indicate that genetic divergence can be promoted by asynchronous breeding lag in the absence of geographic barriers in species where breeding is associated with water availability, but such effects may not be stable enough through time to influence macroevolutionary patterns.

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