lecture 06 - how organisms adapt and evolve Flashcards
(34 cards)
what is evolution?
process driven by natural selection that changes populations of organisms of organisms over time, leading to speciation
what are the 4 things for natural selection to occur?
heredity, reproduction, physical traits that differ, and variation in the number of offspring produced by each individual
define alleles
different forms of a gene (M, m)
define gene pool
the sum of all the alleles in a population
define evolution
change in allele (or gene) frequencies within a gene pool over time (within a population)
why are individuals variable
they have a genotype and a phenotype
define a phenotype
an attribute of an organism that is observed such as its behaviour, morphology or physiology (how the gene is expressed)
define a genotype
the set of genes an organism has
what does evolution require?
phenotypic variation among individuals that is heritable
what are the results of phenotype variation?
the combined effects of genes and environment (how the gene is expressed and how that gets passed down to offspring)
what is phenotypic plasticity?
variation we see in a phenotype that is the result of environmental variation
what are genetic differences?
phenotypic differences we see that are due to differences in genetic material
what are the mechanisms of evolution?
natural selection
genetic drift
natural selection
- more offspring are produced than can survive
- traits vary among individuals within a population and may be heritable
- some heritable traits give individuals an advantage
- advantageous traits that provide higher fitness, become more common
what is direction selection?
an extreme phenotype becomes more frequent
what is stabilizing selection?
a type of natural selection in which an average phenotype increases in frequency and extreme phenotypes decrease in frequency
what is disruptive selection?
a type of natural selection in which two or more extreme phenotypes become more frequent and the average phenotype becomes less frequent
what is adaptation?
traits that have been selected for through natural selection
what is adaptive radiation?
the diversification of a group of organisms into forms filling different ecological niches
what is speciation?
physical and ecological processes interact with selection and random processes such as drift to produce new species
what is a species?
a name and classification humans give to living things
how are they grouped based on different criteria?
morphological species concept
biological species concept
phylogenetic species concept
what is morphological species concept?
species grouped by morphological similarities?
what is biological species concept?
groups of actually or potentially interbreeding populations which are reproductively isolated from other such groups (they HAVE to be reproductively isolated)
