scholarly journals Contrasting drivers of diversification rates on islands and continents across three passerine families

2019 ◽  
Vol 286 (1915) ◽  
pp. 20191757
Author(s):  
Meaghan Conway ◽  
Brian J. Olsen
Keyword(s):  
Relative Effect ◽  
Range Size ◽  
Relative Importance ◽  
Ecological Specialization ◽  
Diversification Rates ◽  
Speciation Rates ◽  
Bill Morphology ◽  
Spatio Temporal ◽  
Species Specific ◽  
Continuous Index

Diversification rates vary greatly among taxa. Understanding how species-specific traits influence speciation rates will help elucidate mechanisms driving biodiversity over broad spatio-temporal scales. Ecological specialization and range size are two hypothesized drivers of speciation rates, yet each mechanism predicts both increases and decreases in speciation. We constructed a continuous index of specialization using avian bill morphology to determine the relative effect of specialization and range size and shape on speciation rates across 559 species within the Emberizoidea superfamily, a morphologically diverse New World clade. We found a significant positive correlation between specialization and speciation rate and a negative correlation with range size. Only the effect of specialization persisted after removing island endemics, however, suggesting that ecological specialization is an important driver of diversity across large macroevolutionary scales, and the relative importance of specific drivers may differ between islands and continents.

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.

Spatio-temporal and species-specific variation in PBDE levels/patterns in British Columbia's coastal waters

2006 ◽  
Vol 140 (2) ◽  
pp. 355-363 ◽  
Author(s):  
Michael G. Ikonomou ◽  
Marc P. Fernandez ◽  
Zachary L. Hickman
Keyword(s):  
Coastal Waters ◽  
Specific Variation ◽  
Spatio Temporal ◽  
Species Specific

scholarly journals Evolutionary rates of mitochondrial genomes correspond to diversification rates and to contemporary species richness in birds and reptiles

2010 ◽  
Vol 277 (1700) ◽  
pp. 3587-3592 ◽  
Author(s):  
Soo Hyung Eo ◽  
J. Andrew DeWoody
Keyword(s):  
Species Richness ◽  
Nuclear Data ◽  
Synonymous Substitution ◽  
Evolutionary Rates ◽  
Rate Variation ◽  
Substitution Rates ◽  
Diversification Rates ◽  
Extinction Process ◽  
Molecular Evolutionary Rates ◽  
Speciation Rates

Rates of biological diversification should ultimately correspond to rates of genome evolution. Recent studies have compared diversification rates with phylogenetic branch lengths, but incomplete phylogenies hamper such analyses for many taxa. Herein, we use pairwise comparisons of confamilial sauropsid (bird and reptile) mitochondrial DNA (mtDNA) genome sequences to estimate substitution rates. These molecular evolutionary rates are considered in light of the age and species richness of each taxonomic family, using a random-walk speciation–extinction process to estimate rates of diversification. We find the molecular clock ticks at disparate rates in different families and at different genes. For example, evolutionary rates are relatively fast in snakes and lizards, intermediate in crocodilians and slow in turtles and birds. There was also rate variation across genes, where non-synonymous substitution rates were fastest at ATP8 and slowest at CO 3. Family-by-gene interactions were significant, indicating that local clocks vary substantially among sauropsids. Most importantly, we find evidence that mitochondrial genome evolutionary rates are positively correlated with speciation rates and with contemporary species richness. Nuclear sequences are poorly represented among reptiles, but the correlation between rates of molecular evolution and species diversification also extends to 18 avian nuclear genes we tested. Thus, the nuclear data buttress our mtDNA findings.

scholarly journals Explaining the ocean's richest biodiversity hotspot and global patterns of fish diversity

2018 ◽  
Vol 285 (1888) ◽  
pp. 20181314 ◽  
Author(s):  
Elizabeth Christina Miller ◽  
Kenji T. Hayashi ◽  
Dongyuan Song ◽  
John J. Wiens
Keyword(s):  
Large Scale ◽  
Fish Diversity ◽  
Relative Importance ◽  
Diversification Rates ◽  
Marine Habitats ◽  
History Of ◽  
Richness Patterns ◽  
Colonization Time ◽  
Almost All

For most marine organisms, species richness peaks in the Central Indo-Pacific region and declines longitudinally, a striking pattern that remains poorly understood. Here, we used phylogenetic approaches to address the causes of richness patterns among global marine regions, comparing the relative importance of colonization time, number of colonization events, and diversification rates (speciation minus extinction). We estimated regional richness using distributional data for almost all percomorph fishes (17 435 species total, including approximately 72% of all marine fishes and approximately 33% of all freshwater fishes). The high diversity of the Central Indo-Pacific was explained by its colonization by many lineages 5.3–34 million years ago. These relatively old colonizations allowed more time for richness to build up through in situ diversification compared to other warm-marine regions. Surprisingly, diversification rates were decoupled from marine richness patterns, with clades in low-richness cold-marine habitats having the highest rates. Unlike marine richness, freshwater diversity was largely derived from a few ancient colonizations, coupled with high diversification rates. Our results are congruent with the geological history of the marine tropics, and thus may apply to many other organisms. Beyond marine biogeography, we add to the growing number of cases where colonization and time-for-speciation explain large-scale richness patterns instead of diversification rates.

Evaluation of fixatives and autofluorescence reduction treatments for marine bivalve larvae

2011 ◽  
Vol 91 (7) ◽  
pp. 1567-1576 ◽  
Author(s):  
S.A. Heaney ◽  
A.P. Maloy ◽  
J.W. Slater
Keyword(s):  
Larval Growth ◽  
Temporal Distribution ◽  
Fluorescein Isothiocyanate ◽  
Plankton Sample ◽  
Larval Abundance ◽  
Marine Bivalve ◽  
Sudan Black B ◽  
Bivalve Larvae ◽  
Spatio Temporal ◽  
Species Specific

Improved understanding of the occurrence and spatio-temporal distribution of bivalve larvae holds significant benefits for ecological studies, shellfisheries management and aquaculture. Morphological methods for identification have proved difficult to develop because of the small size of these larvae and similarities in their shape and colour. Molecular methods based on DNA extraction can confirm the presence of a species in a plankton sample, but without sample sorting and individual larval analysis, provide no estimate of larval abundance and are incapable of providing an estimate of larval growth rate. Fluorescencein situhybridization (FISH) using species-specific DNA probes has the potential to resolve these issues. However, utilization of this technique is constrained by the strong autofluorescence, common in marine larvae. Here we evaluate the effect of eight different fixatives on the autofluorescence intensity of bivalve larvae using fluorescein isothiocyanate (FITC) and Cy3 filters. In addition, fifteen autofluorescence reduction treatments were evaluated and their compatibility with FISH assessed. Relative to fresh larvae, chemically fixed larvae had significantly higher autofluorescence in both filter sets. Larvae preserved by freezing at –80°C exhibited no significant increase in autofluorescence over a 3-year period. Autofluorescence levels were generally lower with the FITC filter set than the Cy3 filter set. For archived larvae preserved in modified saline ethanol and exhibiting fixative-induced autofluorescence, the autofluorescence intensity could be reduced to 20–30% with saturated Sudan Black B and to 30–40% with Chemicon™. Both of these autofluorescence reduction treatments were compatible with subsequent FISH protocols using a FITC-labelled probe.

scholarly journals The Dynamics of Bird Diversity in the New World

2020 ◽  
Vol 69 (6) ◽  
pp. 1180-1199 ◽  
Author(s):  
Antonin Machac
Keyword(s):  
Species Richness ◽  
New World ◽  
Dominant Role ◽  
Bird Diversity ◽  
Biodiversity Hotspots ◽  
Relative Importance ◽  
Diversification Rates ◽  
The Andes ◽  
The Rich ◽  
Over Time

Abstract Three prominent explanations have been proposed to explain the dramatic differences in species richness across regions and elevations, (i) time for speciation, (ii) diversification rates, and (iii) ecological limits. But the relative importance of these explanations and, especially, their interplay and possible synthesis remain largely elusive. Integrating diversification analyses, null models, and geographic information systems, I study avian richness across regions and elevations of the New World. My results reveal that even though the three explanations are differentially important (with ecological limits playing the dominant role), each contributes uniquely to the formation of richness gradients. Further, my results reveal the likely interplay between the explanations. They indicate that ecological limits hinder the diversification process, such that the accumulation of species within a region gradually slows down over time. Yet, it does not seem to converge toward a hard ceiling on regional richness. Instead, species-rich regions show suppressed, but continued, diversification, coupled with signatures of possible competition (esp. Neotropical lowlands). Conversely, species-poor, newly-colonized regions show fast diversification and weak to no signs of competition (esp. Nearctic highlands). These results held across five families of birds, across grid cells, biomes, and elevations. Together, my findings begin to illuminate the rich, yet highly consistent, interplay of the mechanisms that together shape richness gradients in the New World, including the most species-rich biodiversity hotspots on the planet, the Andes and the Amazon. [Biogeography; community; competition; macroevolution; phylogenetics; richness gradient.]

scholarly journals Stress induced gene expression drives transient DNA methylation changes at adjacent repetitive elements

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
David Secco ◽  
Chuang Wang ◽  
Huixia Shou ◽  
Matthew D Schultz ◽  
Serge Chiarenza ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Temporal Dynamics ◽  
Phosphate Starvation ◽  
A Genome ◽  
Genome Bisulfite Sequencing ◽  
Induced Genes ◽  
Spatio Temporal ◽  
Meiotic Transmission ◽  
Species Specific ◽  
Induced Changes

Cytosine DNA methylation (mC) is a genome modification that can regulate the expression of coding and non-coding genetic elements. However, little is known about the involvement of mC in response to environmental cues. Using whole genome bisulfite sequencing to assess the spatio-temporal dynamics of mC in rice grown under phosphate starvation and recovery conditions, we identified widespread phosphate starvation-induced changes in mC, preferentially localized in transposable elements (TEs) close to highly induced genes. These changes in mC occurred after changes in nearby gene transcription, were mostly DCL3a-independent, and could partially be propagated through mitosis, however no evidence of meiotic transmission was observed. Similar analyses performed in Arabidopsis revealed a very limited effect of phosphate starvation on mC, suggesting a species-specific mechanism. Overall, this suggests that TEs in proximity to environmentally induced genes are silenced via hypermethylation, and establishes the temporal hierarchy of transcriptional and epigenomic changes in response to stress.

How do meteorological variables and topography control species-specific water uptake strategy along a forested hillslope?

2020 ◽  
Author(s):  
Ginevra Fabiani ◽  
Daniele Penna ◽  
Julian Klaus
Keyword(s):  
Isotopic Composition ◽  
Soil Water ◽  
Water Uptake ◽  
Temporal Dynamics ◽  
Growth Parameters ◽  
Stream Water ◽  
Growing Season ◽  
Grab Sampling ◽  
Spatio Temporal ◽  
Species Specific

<p>In the face of current global warming conditions, temperate forest ecosystems are expected to be strongly affected by temperature increase and more frequent and intense water shortage. This leads to severe stress for forest vegetation in many temperate systems. Therefore, understanding the vegetation water use in temperate forests is urgently needed for more effective forest management strategies. Root water uptake (RWU) is a species-specific trait (tree physiology and root architecture) and its spatio-temporal patterns are controlled by a range of site-specific (e.g., topography, geology, pedology) and meteorological factors (e.g., temperature, soil humidity, rainfall.</p><p>In the present study, we use stable water isotopologues as ecohydrological tracers combined with continuous measurement of hydrometeorological (weather variables, groundwater levels, soil moisture, streamflow) and physiological (sap flow, radial stem growth) parameters to investigate the spatio-temporal dynamics of water uptake for beech (Fagus sylvatica L.) and sessile oak (Quercus petraea (Matt.) Liebl) trees along a hillslope in a Luxemburgish catchment.</p><p>Fortnightly field campaigns were carried out during the growing season (April-October) 2019 to sample water from xylem, soil water at different depths, groundwater, stream water, and precipitation. Soil water isotopic composition and xylem water were extracted via cryogenic distillation. Grab sampling was performed for the other water pools. The isotopic composition was determined through laser spectroscopy and mass spectrometry (for xylem samples only).</p><p>From preliminary results, the isotopic composition of xylem water shows a marked seasonal variability suggesting a plasticity in RWU or a change in the isotopic composition of the water pools over the growing season. Moreover, beech and oak trees exhibit different uptake strategies when water supply is low. Within the range of observed groundwater variation topography does not play a statistically significant role on RWU.</p>

scholarly journals Millennial-scale faunal record reveals differential resilience of European large mammals to human impacts across the Holocene

2016 ◽  
Vol 283 (1827) ◽  
pp. 20152152 ◽  
Author(s):  
Jennifer J. Crees ◽  
Chris Carbone ◽  
Robert S. Sommer ◽  
Norbert Benecke ◽  
Samuel T. Turvey
Keyword(s):  
Large Scale ◽  
Temporal Dynamics ◽  
Human Impacts ◽  
Biodiversity Loss ◽  
Mammal Species ◽  
The Holocene ◽  
Range Change ◽  
Spatio Temporal ◽  
Patterns And Processes ◽  
Species Specific

The use of short-term indicators for understanding patterns and processes of biodiversity loss can mask longer-term faunal responses to human pressures. We use an extensive database of approximately 18 700 mammalian zooarchaeological records for the last 11 700 years across Europe to reconstruct spatio-temporal dynamics of Holocene range change for 15 large-bodied mammal species. European mammals experienced protracted, non-congruent range losses, with significant declines starting in some species approximately 3000 years ago and continuing to the present, and with the timing, duration and magnitude of declines varying individually between species. Some European mammals became globally extinct during the Holocene, whereas others experienced limited or no significant range change. These findings demonstrate the relatively early onset of prehistoric human impacts on postglacial biodiversity, and mirror species-specific patterns of mammalian extinction during the Late Pleistocene. Herbivores experienced significantly greater declines than carnivores, revealing an important historical extinction filter that informs our understanding of relative resilience and vulnerability to human pressures for different taxa. We highlight the importance of large-scale, long-term datasets for understanding complex protracted extinction processes, although the dynamic pattern of progressive faunal depletion of European mammal assemblages across the Holocene challenges easy identification of ‘static’ past baselines to inform current-day environmental management and restoration.

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