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The Evidence for Evolution

The Evidence for Evolution

Genetic variations accumulating within populations over generations give rise to biological evolution. Evolutionary changes can result in the formation of novel varieties and entire new species. These changes are responsible for the diverse forms of life inhabiting the planet. The evidence for evolution suggests that all living organisms descended from common ancestors.

What is Population Genetics?

What is Population Genetics?

A population is composed of members of the same species that simultaneously live and interact in the same area. When individuals in a population breed, they pass down their genes to their offspring. Many of these genes are polymorphic, meaning that they occur in multiple variants. Such variations of a gene are referred to as alleles. The collective set of all the alleles within a population is known as the gene pool.

Conservation of Declining Populations

Conservation of Declining Populations

Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent populations from going extinct.

Limits to Natural Selection

Limits to Natural Selection

Organisms that are well-adapted to their environment are more likely to survive and reproduce. However, natural selection does not lead to perfectly adapted organisms. Several factors constrain natural selection.

Gene Flow

Gene Flow

Gene flow is the transfer of genes among populations, resulting from either the dispersal of gametes or from the migration of individuals.

Hardy-Weinberg Principle

Hardy-Weinberg Principle

Diploid organisms have two alleles of each gene, one from each parent, in their somatic cells. Therefore, each individual contributes two alleles to the gene pool of the population. The gene pool of a population is the sum of every allele of all genes within that population and has some degree of variation. Genetic variation is typically expressed as a relative frequency, which is the percentage of the total population that has a given allele, genotype or phenotype.

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A Method for Investigating Change Blindness in Pigeons (Columba Livia)

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Populations and pigeons: prosaic pluralism about evolutionary causes.

Marshall Abrams¹

¹Department of Philosophy, University of Alabama at Birmingham, 900 13th Street South, HB414A, Birmingham, AL 35294-1260, USA. mabrams@uab.edu

Studies in History and Philosophy of Biological and Biomedical Sciences

|August 6, 2013

Summary

The description of biological populations influences natural selection conclusions. This study argues that population descriptions can capture different causal relations, resolving debates on natural selection as a cause in evolution.

Keywords:

Causation Levels Natural selection Population Probability

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Area of Science:

Evolutionary biology
Philosophy of biology

Background:

Debate exists on whether natural selection is a cause or an outcome.
Previous arguments suggest population description impacts natural selection conclusions.

Purpose of the Study:

To re-evaluate Walsh's arguments on natural selection and population description.
To demonstrate how population descriptions can capture distinct causal relations.
To offer a new perspective on causation in evolutionary processes.

Main Methods:

Analysis of existing arguments by Walsh (2007, 2010).
Development of a novel argument addressing overlooked biological details.
Illustration using a biological example demonstrating description-dependence.
Examination of contemporary research on human evolution.

Main Results:

Walsh's arguments are shown to be flawed due to overlooking biological details and description-dependence.
Biologists exhibit flexibility in population descriptions, as seen in human evolution studies.
Description-dependence is compatible with capturing different causal relations.

Conclusions:

Natural selection remains a causal factor despite description-dependence.
The study refutes specific arguments by Walsh (2007, 2010).
A revised understanding of causation in evolutionary biology is proposed.