Chapter 18 Flashcards
Heritable change in a population over time. Describes a mechanism for how species change over time. Change in populations inherited traits over time. Populations do this but not individuals.
Evolution
Conceived the actual mechanism for evolution. Observed on his travels that the species were clearly similar, yet had distinct differences.
Ex.) The ground finches comprised of several species with a unique beak shape. He observed that these species had various beak sizes and shapes with very small differences between the most similar. He observed those finches resembled other ones on South African mainland. He believed the island species might be modified from one of the original mainland species.
Charles Darwin
Leads to evolutionary change. Process in which individuals with favorable inherited traits are more likely to survive and reproduce. “survival of the fittest.” Reproduction of individuals with favorable traits that are able to survive environmental change because of those traits.
Natural Selection.
When can natural selection only take place:
- can only take place if there is variation (differences) among individuals
- must have genetic basis– because selection will not lead to chance in next generation if so.
Genetic diversity comes from:
1.) Mutation
2.) Sexual Reproduction
A change in DNA, is the ultimate source of new alleles, or new genetic variation in any population. Affects organisms phenotype: reduces or benefits fitness (may also have no effect) , lower likelihood of survival
Mutation
Leads to diversity when 2 parents reproduce, unique combos of alleles assemble to produce the unique genotypes and thus phenotypes in each offspring.
Sexual reproduction
A trait with a current functional role in life of an organism that is maintained and evolved by means of natural selection. Heritable trait that helps an organisms survival and reproduction in its present environment.
Adaptation
Observation of Evolution:
1.) Direct Observations
2.) Homology
3.) Convergent Evolution
4.) The fossil record
5.) Biogeography
Two examples provide evidence for natural selection: natural selection in response to introduced species and the evolution of drug-resistant bacteria. ex.) Florida lizard
Direct Observations
Similarity resulting from common ancestry.
Homology
anatomical resemblances that represent variations on a structural theme present in a common ancestor.
Homologous structures
Are remnants of features that served important functions in the organisms ancestors. Unused structures without function. Ex.) wings on flightless birds, leaves on cacti, and hind leg bones on whales.
Vestigial structures
Where similar traits evolve independently in species that do not share a recent common ancestry. The evolution of similar or analogous features. in distantly related groups. Ex.) bat and insect wings have evolved from very different original structures. The trait in the two species came to b similar in structure and have the same function (flying) but did so separately from each other.
ex.) Artic fox and ptarmigan live in artic region, have white phenotype, do not occur from common ancestry. Just a benefit of predators not seeing them.
Convergent Evolution
Traits arise when groups independently adapt to similar environments in similar ways. When similar characteristics occur because of environmental constraints and not due to a close evolutionary relationship.
ex.) Insects use wings to fly like bats and birds, but the wing structure and embryonic origin are completely different.
(these are still homologous remember! but while wings are these…)
Analogous (homoplasy)
Groups of organisms that become tremendously different from each other. 2 species that evolve in diverse direction from a common point. ex.) The reproduction of flowering plants share same basic anatomies; however they can look very different as a result of selection in different physical environments and adaptations to different kinds of pollinators.
Divergent Evolution
The extinction of species. The origin of new groups. Changes within groups over time.
Fossil Records
The scientific study of the geographic distribution of species. Pangea–Geographically separated species.
Biogeography
species that are not found anywhere else in the world. basis from biogeography. evolution occurs in different location and not found anywhere else other than that different location.
Endemic
Process by which one species splits into two or more species.
Speciation
Consists of change in allele frequency in a population over time.
Microevolution
Refers to broad patterns of evolutionary change above the species level.
Macroevolution
Myths of Evolution:
- Evolution is just a theory
- Individuals evolve (they don’t)
- Evolution explains the origin of life
- Organisms evolve on purpose
Definitions of Species include:
1.) Biological Species Concept
2.) Morphological Species Concept
3.) Ecological Species Concept
4.) Phylogenetic Species Concept
A species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring.
Biological Species Concept
the existence of biological barriers that impede two species from producing viable, fertile offspring. Sometimes hybrids (a cross between 2 species), the offspring of crosses between different species, are successfully produced.
Reproductive Isolation