scholarly journals Heterostyly accelerates diversification via reduced extinction in primroses

2014 ◽  
Vol 281 (1784) ◽  
pp. 20140075 ◽  
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.

scholarly journals Diferentes tasas evolutivas entre grupos de angiospermas. Eudicotiledóneas

2017 ◽  
pp. 137
Author(s):  
Susana Magañón-Puebla
Keyword(s):  
Species Distribution ◽  
Sister Group ◽  
Species Level ◽  
Evolutionary Rates ◽  
Analytical Models ◽  
Extinction Rates ◽  
Speciation Rates ◽  
Tree Models

Applying analytical models to two clades, eudicotyledons and paleoherbs, three filogeny models were explored and analyzed with parameters that vary from low extinction rates to high speciation rates. Filogeny Model I suggest that the probability ty of obtaining a difference in species distribution, between the two sister clades, as the observed, or higher, varies between 15.2% with high speciation rates and 16.7% with low extinction rates. In Filogeny Model II the probability of obtaining a species distribution similar to the observed one or higher, varies between 15.7% with high speciation rates to 17.4% with low extinction rates. In contrast, probability of obtaining a species distribution like the observed or higher in Filogeny Model III varies from 2.5% with high speciation rates to 2.8% with low extinction rates. Accordingly with the tree Models, the probability of obtaining a numerical difference at the species level between eudicotyledons and its sister group are low. However, results suggest the eudicotyledons are characterize by higher evolutionary rates (speciation-extinction) compared with other groups of angiosperms.

scholarly journals Geographic contingency, not species sorting, dominates macroevolutionary dynamics in an extinct clade of neogastropods (Volutospina; Volutidae)

Paleobiology ◽  
2021 ◽  
pp. 1-15
Author(s):  
Dana S. Friend ◽  
Brendan M. Anderson ◽  
Warren D. Allmon
Keyword(s):  
Middle Eocene ◽  
Ecological Factors ◽  
Geographic Range ◽  
Late Eocene ◽  
Range Size ◽  
Species Sorting ◽  
Extinction Rates ◽  
Geographic Range Size ◽  
Speciation Rates ◽  
Planktotrophic Larvae

Abstract Rates of speciation and extinction are often linked to many ecological factors, traits (emergent and nonemergent) such as environmental tolerance, body size, feeding type, and geographic range. Marine gastropods in particular have been used to examine the role of larval dispersal in speciation. However, relatively few studies have been conducted placing larval modes in species-level phylogenetic context. Those that have, have not incorporated fossil data, while landmark macroevolutionary studies on fossil clades have not considered both phylogenetic context and net speciation (speciation–extinction) rates. This study utilizes Eocene volutid Volutospina species from the U.S. Gulf Coastal Plain and the Hampshire Basin, U.K., to explore the relationships among larval mode, geographic range, and duration. Based on the phylogeny of these Volutospina, we calculated speciation and extinction rates in order to compare the macroevolutionary effects of larval mode. Species with planktotrophic larvae had a median duration of 9.7 Myr, which compared significantly to 4.7 Myr for those with non-planktotrophic larvae. Larval mode did not significantly factor into geographic-range size, but U.S. and U.K. species do differ, indicating a locality-specific component to maximum geographic-range size. Non-planktotrophs (NPTs)were absent among the Volutospina species during the Paleocene–early Eocene. The relative proportions of NPTs increased in the early middle Eocene, and the late Eocene was characterized by disappearance of planktotrophs (PTs). The pattern of observed lineage diversity shows an increasing preponderance of NPTs; however, this is clearly driven by a dramatic extinction of PTs, rather than higher NPT speciation rates during the late Eocene. This study adds nuance to paleontology's understanding of the macroevolutionary consequences of larval mode.

scholarly journals Reconciliation ecology and the future of species diversity

Oryx ◽  
2003 ◽  
Vol 37 (2) ◽  
pp. 194-205 ◽  
Author(s):  
Michael L. Rosenzweig
Keyword(s):  
Steady State ◽  
Species Diversity ◽  
Natural Area ◽  
Reconciliation Ecology ◽  
Anthropogenic Habitats ◽  
Extinction Rates ◽  
Broad Array ◽  
Speciation Rates ◽  
Species Area ◽  
Biogeographical Province

Species-area relationships (SPARs) dictate a sea change in the strategies of biodiversity conservation. SPARs exist at three ecological scales: Sample-area SPARs (a larger area within a biogeographical province will tend to include more habitat types, and thus more species, than a smaller one), Archipelagic SPARs (the islands of an archipelago show SPARs that combine the habitat-sampling process with the problem of dispersal to an island), and Interprovincial SPARs (other things being equal, the speciation rates of larger biogeographical provinces are higher and their extinction rates are lower, leading to diversities in proportion to provincial area). SPARs are the products of steady-state dynamics in diversity, and such dynamics appears to have characterized the earth for most of the last 500 million years. As people reduce the area available to wild species, they impose a linear reduction of the earth's species diversity that will follow the largest of these scales, i.e. each 1% reduction of natural area will cost about 1% of steady-state diversity. Reserving small tracts of wild habitat can only delay these reductions. But we can stop most of them by redesigning anthropogenic habitats so that their use is compatible with use by a broad array of other species. That is reconciliation ecology. Many pilot projects, whether intentionally or inadvertently espousing reconciliation ecology, are demonstrating that it can be done.

Milankovitch cycles and their effects on species in ecological and evolutionary time

Paleobiology ◽  
1990 ◽  
Vol 16 (1) ◽  
pp. 11-21 ◽  
Author(s):  
K. D. Bennett
Keyword(s):  
Time Scales ◽  
Climatic Changes ◽  
Milankovitch Cycles ◽  
Mass Extinctions ◽  
Geological Time ◽  
Evolutionary Time ◽  
Abiotic Environment ◽  
Earth History ◽  
Microevolutionary Change ◽  
Second Tier

The Quaternary ice ages were paced by astronomical cycles with periodicities of 20–100 k.y. (Milankovitch cycles). These cycles have been present throughout earth history. The Quaternary fossil record, marine and terrestrial, near to and remote from centers of glaciation, shows that communities of plants and animals are temporary, lasting only a few thousand years at the most. Response of populations to the climatic changes of Quaternary Milankovitch cycles can be taken as typical of the way populations have behaved throughout earth history. Milankovitch cycles thus force an instability of climate and other aspects of the biotic and abiotic environment on time scales much less than typical species durations (1–30 m.y.). Any microevolutionary change that accumulates on a time scale of thousands of years is likely to be lost as communities are reorganized following climatic changes. A four-tier hierarchy of time scales for evolutionary processes can be constructed as follows: ecological time (thousands of years), Milankovitch cycles (20–100 k.y.), geological time (millions of years), mass extinctions (approximately 26 m.y.). “Ecological time” and “geological time” are defined temporally as the intervals between events of the second and fourth tiers, respectively. Gould's (1985) “paradox of the first tier” can be resolved, at least in part, through the undoing of Darwinian natural selection at the first tier by Milankovitch cycles at the second tier.

scholarly journals The life cycle of Drosophila orphan genes

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Nicola Palmieri ◽  
Carolin Kosiol ◽  
Christian Schlötterer
Keyword(s):  
Life Cycle ◽  
Time Scales ◽  
High Rate ◽  
Sequence Evolution ◽  
Functional Requirements ◽  
Evolutionary Time ◽  
Orphan Genes ◽  
Functional Conservation ◽  
Close Relatives ◽  
Obscura Group

Orphans are genes restricted to a single phylogenetic lineage and emerge at high rates. While this predicts an accumulation of genes, the gene number has remained remarkably constant through evolution. This paradox has not yet been resolved. Because orphan genes have been mainly analyzed over long evolutionary time scales, orphan loss has remained unexplored. Here we study the patterns of orphan turnover among close relatives in the Drosophila obscura group. We show that orphans are not only emerging at a high rate, but that they are also rapidly lost. Interestingly, recently emerged orphans are more likely to be lost than older ones. Furthermore, highly expressed orphans with a strong male-bias are more likely to be retained. Since both lost and retained orphans show similar evolutionary signatures of functional conservation, we propose that orphan loss is not driven by high rates of sequence evolution, but reflects lineage-specific functional requirements.

scholarly journals Extinction in complex communities as driven by adaptive dynamics

2021 ◽  
Author(s):  
Vu Nguyen ◽  
Dervis Vural
Keyword(s):  
Time Scales ◽  
Computer Simulations ◽  
Analytical Solutions ◽  
Adaptive Dynamics ◽  
Mathematical Framework ◽  
Evolutionary Time ◽  
Community Interactions ◽  
Fitness Functions ◽  
Evolutionary Changes

In a complex community, species continuously adapt to each other. On rare occasions, the adaptation of a species can lead to the extinction of others, and even its own. ``Adaptive dynamics'' is the standard mathematical framework to describe evolutionary changes in community interactions, and in particular, predict adaptation driven extinction. Unfortunately, most authors implement the equations of adaptive dynamics through computer simulations, that require assuming a large number of questionable parameters and fitness functions. In this study we present analytical solutions to adaptive dynamics equations, thereby clarifying how outcomes depend on any computational input. We develop general formulas that predict equilibrium abundances over evolutionary time scales. Additionally, we predict which species will go extinct next, and when this will happen.

The improbability of animal phyla with few species

Paleobiology ◽  
1983 ◽  
Vol 9 (2) ◽  
pp. 97-106 ◽  
Author(s):  
Richard R. Strathmann ◽  
Montgomery Slatkin
Keyword(s):  
Short Duration ◽  
Alternative Model ◽  
Death Process ◽  
Birth And Death Process ◽  
Monophyletic Clade ◽  
Number Of Species ◽  
Extinction Rates ◽  
Animal Phyla ◽  
Speciation Rates ◽  
Initial Radiation

At present there are many animal phyla that contain only a few species. The existence of these small phyla can be used to test assumptions about speciation and extinction in multicellular animals.We first model the number of species in a monophyletic clade with a birth and death process that assumes rates of speciation and extinction are constant. If no new phyla have evolved since the Cambrian and speciation and extinction rates for minor phyla are similar to or greater than those estimated from fossils, then our model shows that the probabilities of minor phyla surviving to the present are small. Random variation in extinction and speciation rates does not improve the chances for persistence. If speciation rates exceed extinction rates at the initial radiation of the clade, but before the clade becomes large, speciation rates come to equal extinction rates and both are low, persistence from before the Ordovician up to the present becomes likely. These models show that if speciation and extinction rates are independent of the number of species in a clade, then conditions before the Ordovician strongly influence today's distribution of species among taxa.We also discuss a model in which speciation and extinction rates depend on the number of species in a clade. This alternative model can account for the persistence of phyla with few species to the present and predicts a short duration for phyla that did not exceed a threshold number of species.

scholarly journals Climate cooling and clade competition likely drove the decline of lamniform sharks

2019 ◽  
Vol 116 (41) ◽  
pp. 20584-20590 ◽  
Author(s):  
Fabien L. Condamine ◽  
Jules Romieu ◽  
Guillaume Guinot
Keyword(s):  
Evolutionary Biology ◽  
Extinction Risk ◽  
Research Question ◽  
Apex Predators ◽  
Extinction Rates ◽  
Extant Species ◽  
Speciation Rates ◽  
Sister Relationships ◽  
Abiotic And Biotic Factors ◽  
Climate Cooling

Understanding heterogeneity in species richness between closely related clades is a key research question in ecology and evolutionary biology. Multiple hypotheses have been proposed to interpret such diversity contrasts across the tree of life, with most studies focusing on speciation rates to explain clades’ evolutionary radiations, while often neglecting extinction rates. Here we study a notorious biological model as exemplified by the sister relationships between mackerel sharks (Lamniformes, 15 extant species) and ground sharks (Carcharhiniformes, ∼290 extant species). Using a comprehensive fossil dataset, we found that the diversity dynamics of lamniforms waxed and waned following repeated cycles of radiation phases and declining phases. Radiation phases peaked up to 3 times the current diversity in the early Late Cretaceous. In the last 20 million years, the group declined to its present-day diversity. Along with a higher extinction risk for young species, we further show that this declining pattern is likely attributed to a combination of abiotic and biotic factors, with a cooling-driven extinction (negative correlation between temperature and extinction) and clade competition with some ground sharks. Competition from multiple clades successively drove the demise and replacement of mackerel sharks due to a failure to originate facing the rise of ground sharks, particularly since the Eocene. These effects came from ecologically similar carcharhiniform species inhibiting diversification of medium- and large-sized lamniforms. These results imply that the interplay between abiotic and biotic drivers had a substantial role in extinction and speciation, respectively, which determines the sequential rise and decline of marine apex predators.

Phylogenies and angiosperm diversification

Paleobiology ◽  
1993 ◽  
Vol 19 (2) ◽  
pp. 141-167 ◽  
Author(s):  
James A. Doyle ◽  
Michael J. Donoghue
Keyword(s):  
Early Cretaceous ◽  
Phylogenetic Trees ◽  
Sister Group ◽  
Late Triassic ◽  
Tectonic Activity ◽  
Crown Group ◽  
Extrinsic Factors ◽  
Angiosperm Diversification ◽  
Stem Lineage ◽  
Cladistic Analyses

Approaches to patterns of diversification based on counting taxa at a given rank can be misleading, even when all taxa are monophyletic. Such “rank-based” approaches are unable to reflect a hierarchy of evolutionary events because taxa of the same rank cannot be nested within one another. Phylogenetic trees specify an order of origination of characters and clades and can therefore be used in some cases to test hypotheses on causal relationships between characters and changes in diversity. “Tree-thinking” also clarifies discussions of the age of groups, by distinguishing between splitting of the stem-lineage from its sister group and splitting of the crown-group into extant clades.Cladistic evidence that Pentoxylon, Bennettitales, and Gnetales are the sister group of angiosperms implies that the angiosperm line (angiophytes) existed by the Late Triassic. The presence of primitive members of five basic angiosperm clades indicates that the crown-group (angiosperms) had begun to diversify by the mid-Early Cretaceous (Barremian-Aptian), but not necessarily much earlier. The greatest unresolved issue raised by cladistic analyses concerns the fact that the angiosperm tree can be rooted in two almost equally parsimonious positions. Trees rooted near Magnoliales (among “woody magnoliids”) suggest that the angiosperm radiation may have been triggered by the origin of intrinsic traits, e.g., a fast-growing, rhizomatous habit in the paleoherb and eudicot subgroup. However, trees rooted among paleoherbs, which are favored by rRNA data, imply that these traits are basic for angiosperms as a whole. This could mean that the crown-group originated not long before its radiation, or, if it did originate earlier, that its radiation was delayed due to extrinsic factors. Such factors could be a trend from environmental homogeneity and stability in the Jurassic to renewed tectonic activity and disturbance in the Early Cretaceous. Potentially relevant pre-Cretaceous fossils cannot be placed with confidence, but may be located along the stem-lineage (stem angiophytes); their generally paleoherb-like features favor the paleoherb rooting. The history of angiophytes may parallel that of Gnetales: some diversification of the stem-lineage in the Late Triassic, near disappearance in the Jurassic, and vigorous radiation of the crown-group in the Early Cretaceous.

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