scholarly journals The Effects of Social Structure, Geographical Structure, and Population Size on the Evolution of Mitochondrial DNA: II. Molecular Clocks and the Lineage Sorting Period

1999 ◽  
Vol 48 (5) ◽  
pp. 628-629 ◽  
Author(s):  
Guy A. Hoelzer ◽  
Joel Wallman ◽  
Don J. Melnick
Keyword(s):  
Mitochondrial Dna ◽  
Social Structure ◽  
Population Size ◽  
Molecular Clocks ◽  
Lineage Sorting ◽  
Geographical Structure

scholarly journals Social structure and demography of a remnant Asian elephant Elephas maximus population and the implications for survival

Oryx ◽  
2020 ◽  
pp. 1-6
Author(s):  
Lauren J. Hale ◽  
Kun Shi ◽  
Tania C. Gilbert ◽  
Kelvin S.-H. Peh ◽  
Philip Riordan
Keyword(s):  
Social Structure ◽  
Population Size ◽  
Total Population ◽  
Camera Traps ◽  
Asian Elephant ◽  
Elephas Maximus ◽  
Effective Density ◽  
Anthropogenic Pressures ◽  
Sex Ratio Bias ◽  
Elephant Population

Abstract The Asian elephant Elephas maximus is at risk of extinction as a result of anthropogenic pressures, and remaining populations are often small and fragmented remnants, occupying a fraction of the species' former range. Once widely distributed across China, only a maximum of 245 elephants are estimated to survive across seven small populations. We assessed the Asian elephant population in Nangunhe National Nature Reserve in Lincang Prefecture, China, using camera traps during May–July 2017, to estimate the population size and structure of this genetically important population. Although detection probability was low (0.31), we estimated a total population size of c. 20 individuals, and an effective density of 0.39 elephants per km2. Social structure indicated a strong sex ratio bias towards females, with only one adult male detected within the population. Most of the elephants associated as one herd but three adult females remained separate from the herd throughout the trapping period. These results highlight the fragility of remnant elephant populations such as Nangunhe and we suggest options such as a managed metapopulation approach for their continued survival in China and more widely.

scholarly journals Geographical and social isolation drive the evolution of Austronesian languages

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243171
Author(s):  
Cecilia Padilla-Iglesias ◽  
Erik Gjesfjeld ◽  
Lucio Vinicius
Keyword(s):  
Social Structure ◽  
Population Size ◽  
Social Isolation ◽  
Linguistic Diversity ◽  
Cultural Group ◽  
Geographical Isolation ◽  
Austronesian Languages ◽  
New Words ◽  
Gain Loss

The origins of linguistic diversity remain controversial. Studies disagree on whether group features such as population size or social structure accelerate or decelerate linguistic differentiation. While some analyses of between-group factors highlight the role of geographical isolation and reduced linguistic exchange in differentiation, others suggest that linguistic divergence is driven primarily by warfare among neighbouring groups and the use of language as marker of group identity. Here we provide the first integrated test of the effects of five historical sociodemographic and geographic variables on three measures of linguistic diversification among 50 Austronesian languages: rates of word gain, loss and overall lexical turnover. We control for their shared evolutionary histories through a time-calibrated phylogenetic sister-pairs approach. Results show that languages spoken in larger communities create new words at a faster pace. Within-group conflict promotes linguistic differentiation by increasing word loss, while warfare hinders linguistic differentiation by decreasing both rates of word gain and loss. Finally, we show that geographical isolation is a strong driver of lexical evolution mainly due to a considerable drift-driven acceleration in rates of word loss. We conclude that the motor of extreme linguistic diversity in Austronesia may have been the dispersal of populations across relatively isolated islands, favouring strong cultural ties amongst societies instead of warfare and cultural group marking.

scholarly journals Mitochondrial DNA Sequence Diversity in Mammals: A Correlation between the Effective and Census Population Sizes

2020 ◽  
Vol 12 (12) ◽  
pp. 2441-2449
Author(s):  
Jennifer James ◽  
Adam Eyre-Walker
Keyword(s):  
Mitochondrial Dna ◽  
Metabolic Rate ◽  
Population Size ◽  
Effective Population Size ◽  
Dna Sequence ◽  
Range Size ◽  
Effective Population ◽  
Population Sizes ◽  
Census Population Size ◽  
The Relationship

Abstract What determines the level of genetic diversity of a species remains one of the enduring problems of population genetics. Because neutral diversity depends upon the product of the effective population size and mutation rate, there is an expectation that diversity should be correlated to measures of census population size. This correlation is often observed for nuclear but not for mitochondrial DNA. Here, we revisit the question of whether mitochondrial DNA sequence diversity is correlated to census population size by compiling the largest data set to date, using 639 mammalian species. In a multiple regression, we find that nucleotide diversity is significantly correlated to both range size and mass-specific metabolic rate, but not a variety of other factors. We also find that a measure of the effective population size, the ratio of nonsynonymous to synonymous diversity, is also significantly negatively correlated to both range size and mass-specific metabolic rate. These results together suggest that species with larger ranges have larger effective population sizes. The slope of the relationship between diversity and range is such that doubling the range increases diversity by 12–20%, providing one of the first quantifications of the relationship between diversity and the census population size.

scholarly journals Hominin evolution was caused by introgression from Gorilla

2018 ◽  
Author(s):  
Johan Nygren
Keyword(s):  
Mitochondrial Dna ◽  
Conclusive Evidence ◽  
Lineage Sorting ◽  
Chromosome 5 ◽  
Hominin Evolution

ABSTRACT: The discovery of Paranthropus deyiremeda in 3.3–3.5 million year old fossil sites in Afar, together with 30% of the gorilla genome showing lineage sorting between humans and chimpanzees, and a NUMT (“nuclear mitochondrial DNA segment”) on chromosome 5 that is shared by both gorillas, humans and chimpanzees, and shown to have diverged at the time of the Pan-Homo split rather than the Gorilla/Pan-Homo split, provides conclusive evidence that introgression from the gorilla lineage caused the Pan-Homo split, and the speciation of both the Australopithecus lineage and the Paranthropus lineage.

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