scholarly journals No association between plant mating system & geographic range overlap

2015 ◽  
Author(s):  
Dena Grossenbacher ◽  
Ryan Briscoe Runquist ◽  
Emma Goldberg ◽  
Yaniv Brandvain
Keyword(s):  
Mating System ◽  
Plant Species ◽  
Divergence Time ◽  
Flowering Plant ◽  
Divergence Time Estimates ◽  
Species Pairs ◽  
Self Fertilization ◽  
Range Overlap ◽  
Using Data ◽  
Close Relatives

Premise of the Study: Automatic self-fertilization may influence the geography of speciation, promote reproductive isolation between incipient species, and lead to ecological differentiation. As such, selfing taxa are predicted to co-occur more often with their closest relatives than are outcrossing taxa. Despite suggestions that this pattern may be general, the extent to which mating system influences range overlap in close relatives has not been tested formally across a diverse group of plant species pairs. Methods: We test for a difference in range overlap between species pairs where zero, one, or both species are selfers, using data from 98 sister species pairs in 20 genera across 15 flowering plant families. We also use divergence time estimates from time-calibrated phylogenies to ask how range overlap changes with divergence time and whether this effect depends on mating system. Key Results: We find no evidence that automatic self-fertilization influences range overlap of closely related plant species. Sister pairs with more recent divergence times had modestly greater range overlap, but this effect did not depend on mating system. Conclusions: The absence of a strong influence of mating system on range overlap suggests that mating system plays a minor or inconsistent role compared to many other mechanisms potentially influencing the co-occurrence of close relatives.

scholarly journals Tempo and timing of ecological trait divergence in bird speciation

2016 ◽  
Author(s):  
Jay P. McEntee ◽  
Joseph A. Tobias ◽  
Catherine Sheard ◽  
J. Gordon Burleigh
Keyword(s):  
Divergence Time ◽  
Character Displacement ◽  
Allopatric Speciation ◽  
Range Data ◽  
Geographical Isolation ◽  
Ecological Traits ◽  
Trait Divergence ◽  
Divergence Time Estimates ◽  
Time Estimates ◽  
Species Pairs

Summary paragraphOrganismal traits may evolve either gradually or in rapid pulses followed by periods of stasis, but the relative importance of these evolutionary models in generating biodiversity has proven difficult to resolve1,2. In addition, while it is often assumed that pulses of trait evolution are associated with speciation events, few studies have explicitly examined how the tempo of trait divergence varies with respect to different geographical phases of speciation. Thus, we still know little about the trajectories of trait divergence over timescales relevant to speciation, or the extent to which these trajectories are shaped by variation in geographical isolation and overlap (sympatry) among incipient species. Here, we combine divergence time estimates, trait measurements, and geographic range data for avian sister species pairs worldwide to examine the tempo and timing of trait divergence during allopatric speciation. We show that divergence in two important ecological traits—?body mass and beak morphology—is best explained by a model including pulses of divergence and periods of relative stasis. We also infer that trait divergence pulses often precede sympatry, and that pulses leading to greater trait disparity are associated with earlier transitions to sympatry. These findings suggest that early pulses of trait divergence promote subsequent transitions to sympatry, rather than such pulses occurring after sympatry has been established, for example via character displacement3. Incorporating pulsed divergence models into allopatric speciation theory helps to resolve some apparently contradictory observations, including widespread instances of both rapid sympatry and prolonged geographical exclusion4-6.

scholarly journals The geography and ecology of plant speciation: range overlap and niche divergence in sister species

2014 ◽  
Vol 281 (1778) ◽  
pp. 20132980 ◽  
Author(s):  
Brian L. Anacker ◽  
Sharon Y. Strauss
Keyword(s):  
Evolutionary Biology ◽  
Character Displacement ◽  
Sister Species ◽  
Fine Scale ◽  
Species Pairs ◽  
Shared Ancestry ◽  
Ecological Shifts ◽  
Range Overlap ◽  
Close Relatives ◽  
Age Range

A goal of evolutionary biology is to understand the roles of geography and ecology in speciation. The recent shared ancestry of sister species can leave a major imprint on their geographical and ecological attributes, possibly revealing processes involved in speciation. We examined how ecological similarity, range overlap and range asymmetry are related to time since divergence of 71 sister species pairs in the California Floristic Province (CFP). We found that plants exhibit strikingly different age-range correlation patterns from those found for animals; the latter broadly support allopatric speciation as the primary mode of speciation. By contrast, plant sisters in the CFP were sympatric in 80% of cases and range sizes of sisters differed by a mean of 10-fold. Range overlap and range asymmetry were greatest in younger sisters. These results suggest that speciation mechanisms broadly grouped under ‘budding’ speciation, in which a larger ranged progenitor gives rise to a smaller ranged derivative species, are probably common. The ecological and reproductive similarity of sisters was significantly greater than that of sister–non-sister congeners for every trait assessed. However, shifts in at least one trait were present in 93% of the sister pairs; habitat and soil shifts were especially common. Ecological divergence did not increase with range overlap contrary to expectations under character displacement in sympatry. Our results suggest that vicariant speciation is more ubiquitous in animals than plants, perhaps owing to the sensitivity of plants to fine-scale environmental heterogeneity. Despite high levels of range overlap, ecological shifts in the process of budding speciation may result in low rates of fine-scale spatial co-occurrence. These results have implications for ecological studies of trait evolution and community assembly; despite high levels of sympatry, sister taxa and potentially other close relatives, may be missing from local communities.

scholarly journals Reinforcement alone does not explain increased reproductive isolation in sympatry

2021 ◽  
Author(s):  
Daniel R Matute ◽  
Brandon S Cooper
Keyword(s):  
Natural Selection ◽  
Reproductive Isolation ◽  
Significant Role ◽  
Comparative Studies ◽  
Divergence Time ◽  
Sympatric Species ◽  
Geographic Range ◽  
Species Pairs ◽  
Range Overlap ◽  
Toad Bufo

Comparative studies of reproductive isolation (RI) by Coyne and Orr (1, 2) and others indicate a significant role for reinforcing natural selection in Drosophila speciation. The reinforcement hypothesis predicts increased prezygotic, but not postzygotic, RI between sympatric species pairs in response to maladaptive hybridization. We revisit this hypothesis and others using additional Drosophila, Lepidopteran, and toad (Bufo) data. In contrast to the predictions of reinforcement, we find increased premating and postzygotic RI between sympatric Drosophila species, including between recently diverged species pairs, as defined by Coyne and Orr (1) and others (i.e., DNei < 0.5). However, at slightly lower divergence thresholds increased postzygotic RI in sympatry is not statistically significant, while increased premating RI is, generally in agreement with the predictions of reinforcement. While premating data are unavailable, postzygotic RI is also increased between sympatric Lepidopteran and toad (Bufo) species. We find only modest support for 'concordant asymmetries' in premating and postzygotic RI between sympatric Drosophila, described by others as uniquely supporting reinforcement. Finally, the proportion of geographic range overlap shared by species is positively associated with the magnitude of premating RI as predicted by reinforcement, but it is also positively associated with postzygotic RI, which cannot be explained by reinforcement. Taken together, our results demonstrate that comparisons of premating and postzygotic RI in sympatry depend greatly on divergence time, and suggest that fusion, extinction, and/or other mechanisms must combine with reinforcement to generate these patterns.

Molecular phylogeny and divergence time estimates of Penaeid Shrimp Lineages (Decapoda: Penaeidae)

Zootaxa ◽  
2009 ◽  
Vol 2107 (1) ◽  
pp. 41-52 ◽  
Author(s):  
CAROLINA M VOLOCH ◽  
PABLO R FREIRE ◽  
CLAUDIA A M RUSSO
Keyword(s):  
Fossil Record ◽  
Divergence Time ◽  
Penaeid Shrimp ◽  
Divergence Time Estimates ◽  
Time Estimates ◽  
Global Clock ◽  
Late Tertiary ◽  
The Family ◽  
Molecular Studies ◽  
Triassic Period

Fossil record of penaeids indicates that the family exists since the Triassic period, but extant genera appeared only recently in Tertiary strata. Molecular based divergence time estimates on the matter of penaeid radiation were never properly addressed, due to shortcomings of the global molecular clock assumptions. Here, we studied the diversification patterns of the family, uncovering, more specifically, a correlation between fossil and extant Penaeid fauna. For this, we have used a Bayesian framework that does not assume a global clock. Our results suggest that Penaeid genera originated between 20 million years ago and 43 million years ago, much earlier than expected by previous molecular studies. Altogether, these results promptly discard late Tertiary or even Quaternary hypotheses that presumed a major glaciations influence on the diversification patterns of the family.

scholarly journals Out of the Neotropics: Late Cretaceous colonization of Australasia by American arthropods

2012 ◽  
Vol 279 (1742) ◽  
pp. 3501-3509 ◽  
Author(s):  
Prashant P. Sharma ◽  
Gonzalo Giribet
Keyword(s):  
Late Cretaceous ◽  
Divergence Time ◽  
Disjunct Distribution ◽  
Continental Margins ◽  
Divergence Time Estimates ◽  
Evolutionary Origins ◽  
Source Regions ◽  
Time Estimates ◽  
Fiji Islands ◽  
The Pacific

The origins of tropical southwest Pacific diversity are traditionally attributed to southeast Asia or Australia. Oceanic and fragment islands are typically colonized by lineages from adjacent continental margins, resulting in attrition of diversity with distance from the mainland. Here, we show that an exceptional tropical family of harvestmen with a trans-Pacific disjunct distribution has its origin in the Neotropics. We found in a multi-locus phylogenetic analysis that the opilionid family Zalmoxidae, which is distributed in tropical forests on both sides of the Pacific, is a monophyletic entity with basal lineages endemic to Amazonia and Mesoamerica. Indo-Pacific Zalmoxidae constitute a nested clade, indicating a single colonization event. Lineages endemic to putative source regions, including Australia and New Guinea, constitute derived groups. Divergence time estimates and probabilistic ancestral area reconstructions support a Neotropical origin of the group, and a Late Cretaceous ( ca 82 Ma) colonization of Australasia out of the Fiji Islands and/or Borneo, which are consistent with a transoceanic dispersal event. Our results suggest that the endemic diversity within traditionally defined zoogeographic boundaries might have more complex evolutionary origins than previously envisioned.

scholarly journals The role of ultraviolet reflectance and pattern in the pollination system of Hypoxis camerooniana (Hypoxidaceae)

AoB Plants ◽  
2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Yannick Klomberg ◽  
Raissa Dywou Kouede ◽  
Michael Bartoš ◽  
Jan E J Mertens ◽  
Robert Tropek ◽  
...  
Keyword(s):  
Plant Species ◽  
Central Africa ◽  
Complete Removal ◽  
Reproductive Organs ◽  
Specific Pattern ◽  
Flowering Plant ◽  
Pollination System ◽  
Mount Cameroon ◽  
Uv Reflectance ◽  
Montane Grasslands

Abstract Apart from floral morphology and colours perceived by the human eye, ultraviolet (UV) reflectance acts as an important visual advertisement of numerous flowering plant species for pollinators. However, the effect of UV signalling on attracting pollinators of particular plant species is still insufficiently studied, especially in the Afrotropics. Therefore, we studied the pollination system of Hypoxis camerooniana in montane grasslands of Mount Cameroon, West/Central Africa. We focused mainly on the effects of the flowers’ UV reflectance on its visitors. We experimentally removed UV reflection from petals either completely or partially. Thereafter, flower visitors were recorded and pistils were collected post-flowering to quantify germinated pollen tubes per treatments. The most important visitors were bees, followed by flies. Due to their contacts with reproductive organs bees are considered as the primary pollinators. Visitation rates were lower when UV reflectance was completely removed, whereas the decrease of frequency on half-treated flowers did not differ significantly from control treatments. The complete removal of UV also affected bees’ landing behaviour, but not that of flies. We showed that the presence of UV reflectance is more important than UV pattern for bees visiting flowers of H. camerooniana. We hypothesize that exploiting all flowers irrespective of their pattern can be more efficient for pollinators in the open grasslands of high altitudes to spot these relatively scarce flowers by their UV reflectance. Furthermore, we highlight the necessity of both experimental and natural controls in similar studies to control for additional effects of the used UV manipulations. Many plants advertise their flowers with UV reflectance visible to their insect visitors. By manipulating the UV reflectance and pattern of Hypoxis camerooniana in the Afromontane grasslands of Mount Cameroon, we have shown how crucial it is for the predominant visitor, bees. Both bees' preferences for flowers and their behaviour during visits are influenced by changes in UV reflectance. However, the presence of some UV signal is more important than the specific pattern. Especially in montane grasslands with higher UV irradiation, the UV floral colours are important for recognition of flowers by potential pollinators.

scholarly journals Using a GTR+Γ substitution model for dating sequence divergence when stationarity and time-reversibility assumptions are violated

2020 ◽  
Vol 36 (Supplement_2) ◽  
pp. i884-i894
Author(s):  
Jose Barba-Montoya ◽  
Qiqing Tao ◽  
Sudhir Kumar
Keyword(s):  
Divergence Time ◽  
Sequence Divergence ◽  
Molecular Dating ◽  
Divergence Times ◽  
Time Reversibility ◽  
Sequence Alignments ◽  
Divergence Time Estimates ◽  
Time Estimates ◽  
Substitution Process ◽  
The Impact

Abstract Motivation As the number and diversity of species and genes grow in contemporary datasets, two common assumptions made in all molecular dating methods, namely the time-reversibility and stationarity of the substitution process, become untenable. No software tools for molecular dating allow researchers to relax these two assumptions in their data analyses. Frequently the same General Time Reversible (GTR) model across lineages along with a gamma (+Γ) distributed rates across sites is used in relaxed clock analyses, which assumes time-reversibility and stationarity of the substitution process. Many reports have quantified the impact of violations of these underlying assumptions on molecular phylogeny, but none have systematically analyzed their impact on divergence time estimates. Results We quantified the bias on time estimates that resulted from using the GTR + Γ model for the analysis of computer-simulated nucleotide sequence alignments that were evolved with non-stationary (NS) and non-reversible (NR) substitution models. We tested Bayesian and RelTime approaches that do not require a molecular clock for estimating divergence times. Divergence times obtained using a GTR + Γ model differed only slightly (∼3% on average) from the expected times for NR datasets, but the difference was larger for NS datasets (∼10% on average). The use of only a few calibrations reduced these biases considerably (∼5%). Confidence and credibility intervals from GTR + Γ analysis usually contained correct times. Therefore, the bias introduced by the use of the GTR + Γ model to analyze datasets, in which the time-reversibility and stationarity assumptions are violated, is likely not large and can be reduced by applying multiple calibrations. Availability and implementation All datasets are deposited in Figshare: https://doi.org/10.6084/m9.figshare.12594638.

scholarly journals Mating System and Hybridity in Eucalyptus pauciflora

1977 ◽  
Vol 30 (4) ◽  
pp. 337 ◽  
Author(s):  
MA Phillips ◽  
AHD Brown
Keyword(s):  
Mating System ◽  
Outcrossing Rate ◽  
Seedling Stage ◽  
Average Heterozygosity ◽  
Evolutionary Advantage ◽  
Allozyme Polymorphisms ◽  
Self Fertilization

Allozyme polymorphisms at four loci expressed in seeds, and three other loci expressed in seedlings, were used to determine the outcrossing rate in three natural subalpine populations of snow gum (E. paucijlora). Based on the seed loci data, an estimated 37 % of seed was derived from self-fertilization and 63 % from random outcrossing. In the most elevated population the estimate after germination was similar. However, at lower elevations the frequency of effective self-fertilization estimated at the seedling stage was only 16 %. The less elevated populations also showed a greater average heterozygosity and a larger increase in heterozygosity in the adult over the progeny stages. Heterosis apparently operated differentially in these populations-it was more intense at the lower altitudes. Selection in favour of outcrossed individuals may be an important factor in checking the spread through the population of genes which promote self-fertilization, and which would otherwise enjoy an evolutionary advantage.

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