Sentences with phrase «population sizes»

Specification points covered are: Paper 2 Topic 1 (4.5 - homeostasis and response) 4.5.1 - Homeostasis (B5.1 lesson) 4.5.3.2 - Control of blood glucose concentration (B5.1 lesson) 4.5.2.1 - Structure and function (B5.2 lesson) Required practical 7 - plan and carry out an investigation into the effect of a factor on human reaction time (B5.2 lesson) 4.5.3.1 - Human endocrine system (B5.6 lesson) 4.5.3.4 - Hormones in human reproduction (B5.10 lesson) 4.5.3.5 - Contraception (B5.11 lesson) 4.5.3.6 - The use of hormones to treat infertility (HT only)(B5.12 lesson) 4.5.3.7 - Negative feedback (HT only)(B5.13 lesson) Paper 2 topic 2 (4.6 - Inheritance, variation and evolution) 4.6.1.1 - sexual and asexual reproduction (B6.1 lesson) 4.6.1.2 - Meiosis (B6.1 lesson) 4.6.1.4 - DNA and the genome (B6.3 lesson) 4.6.1.6 - Genetic inheritance (B6.5 lesson) 4.6.1.7 - Inherited disorders (B6.6 lesson) 4.6.1.8 - Sex determination (B6.5 lesson) 4.6.2.1 - Variation (B6.9 lesson) 4.6.2.2 - Evolution (B6.10 lesson) 4.6.2.3 - Selective breeding (B6.11 lesson) 4.6.2.4 - Genetic engineering (B6.11 lesson) 4.6.3.4 - Evidence for evolution (B6.16 lesson) 4.6.3.5 - Fossils (B6.16 lesson) 4.6.3.6 - Extinction (B6.16 lesson) 4.6.3.7 - Resistant bacteria (B6.17 lesson) 4.6.4.1 - classification of living organisms (B6.18 lesson) Paper 2 topic 3 (4.7 - Ecology 4.7.1.1 - Communities (B7.1 lesson) 4.7.1.2 - Abiotic factors (B7.1 lesson) 4.7.1.3 - Biotic factors (B7.1 lesson) 4.7.1.4 — Adaptations (B7.2 lesson) 4.7.2.1 - Levels of organisation (feeding relationships + predator - prey cycles)(B7.3 lesson) 4.7.2.1 - Levels of organisation (required practical 9 - population sizes)(B7.4 lesson) 4.7.2.2 - How materials are cycled (B7.5 lesson) 4.7.3.1 - Biodiversity (B7.7 lesson) 4.7.3.6 - Maintaining Biodiversity (B7.7 lesson) 4.7.3.2 - Waste management (B7.9 lesson) 4.7.3.3 - Land use (B7.9 lesson) 4.7.3.4 - Deforestation (B7.9 lesson) 4.7.3.5 - Global warming (B7.9 lesson)

Low - carbohydrate advocates are masters of documenting the efficacy of their philosophy using studies with small population sizes conducted over short time periods — often over weeks or months.

Higher temperatures might also have increased insect population sizes.

To convert to real time (years) and real population sizes, we used a per - generation mutation rate of 1.25 × 10 − 8 and a generation time of 29 years.

The model consists of a population tree with constant population sizes in each branch of the tree and split times.

(c) Applied to hundreds of European individuals, rarecoal estimates split times as indicated on the time axis and population sizes for each branch.

(b) By optimizing the likelihood of the data under the model, we can estimate population sizes and split times.

We first tested rarecoal on simulated data and found that it was able to reconstruct split times and branch population sizes with good accuracy (Fig. 3b), matching allele sharing almost exactly (Supplementary Fig. 6).

Genetic studies using samples along the distribution range of both subspecies and based on a few dozen nuclear markers have revealed loci of relatively high divergence (0.3 — 1.2 %) between subspecies embedded in a genome otherwise characterized by low levels of differentiation and high levels of bidirectional gene flow [21], [24]--[26], likely facilitated by high effective population sizes, high dispersal, and a relatively short generation time [21], [24]--[26].

Estimates of current and ancestral population sizes (Ne1 = 1,600,000; Ne2 = 780,000; Nancestral = 470,000), divergence time (1,800,000 years and assuming a generation time of 1 year), and gene flow (2Nm1autosomal = 1.69; 2Nm2autosomal = 0.83; 2Nm1X - chromosome = 0.38; 2Nm2X - chromosome = 0.26) were obtained from previous studies and inferred using an Isolation - with - Migration model [21], [26].

Effective population sizes (Ne) in rabbits are on the order of 106 [21].

However, to our knowledge the impacts on mosquito population sizes and infection rates remain to be assessed in sufficiently large - scale studies.

In large organisms with relatively small population sizes, such as humans, only in the order of 1 % of the genomic information is shaped by the environment via natural selection.

It even reveals how population sizes of whales have changed during the last million years», summarizes Janke.

Multilocus methods for estimating population sizes, migration rates and divergence time, with applications to the divergence of Drosophila pseudoobscura and D. persimilis

Many higher order vertebrates have low effective population sizes resulting from reduced efficiency of selection [10], suggesting that neutral or mildly deleterious mutations such as some transposon insertions can easily reach fixation.

The difference between age indifferent preference (model AP) and preference for younger females (model YF) in producing a menopausal effect was robust across population sizes and mutation rates.

For instance, a nearly 1 percent average annual death rate for the Soviet Union during World War II versus near zero for India had more to do with India lying thousands of miles away from major theaters of war than population sizes, he argues.

The abundance of turtles in the vicinity of the oil spill was derived by forward - tracking particles from 35 major nesting beaches using knowledge of their population sizes, oceanic - stage durations, and survival rates.

The failure of these early glimmerings of art and sophisticated weaponry to spread and become permanent fixtures of the Middle Paleolithic and the Middle Stone Age seems to have been the result of small population sizes and local extinctions of these populations and their traditions.

«Small population sizes and habitat fragmentation are well known threats to animals with limited mobility, but the impacts of these factors are hard to observe in wild populations,» said Forero - Medina, Species and Science Director for WCS's Colombia Program and a study co-author.

He then combined that with data on threats and population sizes.

He adds, «It's inevitable that there has been some accumulation of deleterious mutations that would have been purged had [humans and chimpanzees] had larger population sizes.»

Often, the data were noisy; there could be lots of ups and downs in population sizes, not always with good explanations for what happened.

The researchers also estimated ancient Denisovan population sizes by using methods to estimate the age of various gene lineages and the amount of difference between the chromosomes the girl inherited from her mother and father.

«Our objective is instead to save as many functioning species as possible — where functioning means reasonable population sizes and the potential for future evolution in a «natural» context.»

And that, he warns, is tricky, involving many different assumptions (about population sizes on different continents, for instance) in the poorly documented period before recorded history.

«We've known for some time that the population sizes of these animals fluctuated throughout the last ice age,» said evolutionary biologist Beth Shapiro of the University of California Santa Cruz, who was also a part of this study.

The new estimates suggest that proposals to lift the International Whaling Commission's 18 - year - old moratorium on commercial whaling are based on a faulty assessment of what constitutes natural population sizes.

They built a mathematical computer model to better understand how this effect might impact on population sizes.

Most of the evidence Atkinson provides of its existence is circumstantial or highly speculative, the only exception being the positive correlation between modern population sizes and number of phonemes in modern languages.

The paper reviews population sizes and trends over time, if known, for each group, ranging from millions of ringed seals to fewer than a hundred beluga whales in Northern Canada's Ungava Bay.

The International Whaling Commission calculates natural population sizes based on analysis of the logbooks of whaling captains and other historical data.

GC - biased gene conversion correlates with recombination rate (86), and new GC alleles reach fixation more easily in species with larger population sizes, which tend to also have smaller body sizes (87).

Ultimately, Falk and Hildebolt found that people living in small - scale societies are not inherently more violent that those living in «civilized» states, and that war deaths scale similarly with population sizes across all levels of human society.

They combined these figures with the European Commission's projections of population sizes.

«If animals can't obtain enough energy, reproductive output and population sizes will suffer.»

In a new article in Current Anthropology, researchers Dean Falk and Charles Hildebolt question some of the assumptions made in Pinker's book, arguing that because rates of violence are blind to actual population sizes, it remains to be seen whether or not the apparent decrease in contemporary violence is an artifact of scaling factors.

This is an integral part of conservation as it enables scientists to identify individuals and estimate population sizes.

Previous research on the pandemic found that environmental factors, timing of the end school holidays, population sizes and air travel contributed to its spread, but this new research has found that transmission occurred primarily over short distances and that school age children may have catalysed the spread.

Despite this unexpected evidence of long - term mating among communities with different cultures and styles, the tempo of genetic change and the population sizes of farmers and hunter - gatherers remain poorly understood, says archaeologist Alasdair Whittle of Cardiff University in Wales.

When he plugged in estimates of prehistoric population sizes and densities, he found that the ideal demographic conditions for advancement began in Africa 100,000 years ago — just when signs of modern behavior first emerge.

Climate change is also impacting species distributions, population sizes, and the timing of reproduction and migration.

«Analyzing nuclear DNA will enhance our understanding of the actual population sizes of the lemurs before they succumbed to extinction, which will better allow us to develop genetic «extinction alerts» for living lemurs,» said study co-author Anne Yoder of Duke..

But an analysis of their DNA suggests that the largest lemurs were more prone to extinction than smaller - bodied species because of their smaller population sizes, according to this team of American and Malagasy researchers.

But the fact that passenger pigeons persisted at relatively small population sizes gives fresh hope to efforts to bring them back — so - called de-extinction.

Lead author Dr Orly Razgour, of the University of Southampton, explained: «Long - lived, slow - reproducing species with smaller population sizes are not likely to be able to adapt to future climate change fast enough through the spread of new mutations arising in the population.

Clarifying population structure and genetic diversity can help in estimating population sizes and crafting management strategies.»

Eight years of data were used to measure how population sizes varied between managed, protected oxbow lakes and open - access lakes.

Hunting and habitat loss now threaten 87 % of large carnivores worldwide, the authors write, and conservationists should do more than keep track of population sizes.