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Exam 1 Flashcards
Ariostotle |
scala nature, said it is like a ladder of life, every rung is "fixed" each step has one species that cannot move up or down |
Linneaus |
father of taxonomy, binomial nomeclatue, allows us to classify organisms based on morphology |
Curvier |
catastrophism, father of paleontology |
catastrophism |
when one species went extinct a new species migrated into the area |
Hutton |
gradualism |
Gradualism |
slow processes create big change overtime |
Lyell |
Uniformitarism |
Uniformitarnism |
Geologic processes occur at the same rage overtime |
Lammarck |
adaptation, use and disuse, inheritance of acquired characteristics |
Darwin |
Theory of evolution, natural selection, influenced by Lyell and Hutton |
Natural Selection |
the mechanism behind evolution, Requires heritable variation, differential reproductive success, selective mating, does not create favorable traits |
Phenotype |
the smallest unit that natural selection can act on |
Intrasexual selection |
direct competition for members of the same sex, for mates. |
Intersexual selection |
mate choice, chosen based on desirable characteristics |
Sexual Dimorphisms |
differences in males and females, EX: size, plumage, manes, antlers
the result of intersexual selection |
Stabilizing selection |
favors the average |
Disruptive/diversifying Selection |
favors both extremes |
Directional selection |
favors one extreme |
Homology |
similarities based on common ancestry |
Anatomical Homologies |
similar physical structures EX: forelimbs of mammals have the same skeletal elements |
Embryological Homologies |
Homologies present during embryological development EX: pharyngeal pouches, gills in fish, Eustachian tubes in humans |
Molecular Homologies |
More closely related organisms have more similar DNA |
Covergent Evolution |
Two different lineages forming similar structures EX: Bird and Bat, Porcupine and Cactus |
Biography |
Geographic Distribution of species |
Population Genetics |
study of genetic variation within populations |
Population |
a group of individuals within the same species |
Species |
a group of populations that can interbreed and produce fertile offspring |
Allele |
a specific form of a gene |
Fixed allele |
an allele that has a frequency of 1 |
Hardy-Weinberg Theorem |
non-evolving population, allele frequencies and genotype frequencies can NOT change overtime |
Microevolution |
changes in the genetic structure of populations overtime |
H-W Assumptions |
Large Population
No net migration
No net mutation
Random mating
No natural selection |
Gene Flow |
migration of alleles, into or out of the population |
Allopatric speciation |
With geographic separation |
Mutation |
original source of variation, the only way to create new alleles |
Genetic Drift |
Acts on small populations, Defined as chance genetic change |
Bottleneck effect |
a disaster reduces the population, genetic diversity is decreased, nothing is selected for pure chance of survival |
Founder Effect |
a group of individuals of a population, by chance migrate and diversify, genetic variation is decreased |
Sexual Recombination |
does not create new alleles, shuffles existing alleles, occurs during meiosis |
diploidy |
two alleles for each gene |
Balanced Polymorphisms |
maintains stable frequencies of 2 or more phenotypes in a population |
Heterozygote advantage |
heterozygotes are favored over the 2 homozygotes |
Frequency dependent selection |
if one allele becomes too common then its survival and reproduction will decrease |
Cline |
variation in a trait across a geographical axis
ex: tree height decreasing with increasing altitude |
Macroevolution |
speciation, formation of new speices |
Anagenesis |
one entire species evolves into a new species, does not increase genetic diversity |
Cladogenesis |
part of a species evolve into a new species, increases genetic diversity |
Biological Species Concept |
a population or group of populations that can interbreed and produce fertile offspring, but cannot produce offspring with other species |
Ecological Species Concept |
defines organisms based on their niche |
Morphological Species Concept |
characterizes species based on their structural features |
Prezygotic Barreiers |
barriers that occur before the zygote is formed/fertilization |
Archean Eon |
involves the origin of earth, first prokaryotic cells appeared and preformed photosynthesis, triggered the oxygen revolution |
Proterozoic Eon |
first eukaryotic cells appeared, first multicellular life (algae), first animal life |
Phanerozoic Eon |
has life as we know it |
Paleozoic Era |
535 mya, oldest era, the age of fishes, plants fungi and arthropods invade land, first land vertebrates (amphibians), first vertebrates with celled eggs amniotes |
Mesozoic Era |
age of dinosaurs, cone-bearing seed plants dominate, first mammals appear |
Cenozoic Era |
diversification of mammals flowering plants birds and insects first humans appear |
why natural selection cannot produce perfect organisms: |
1. selection can only edit existing variations
(favors the fittest phenotypes, new advantageous alleles don't arise on demand)
2. evolution is limited by historical constraints
(each species has a legacy of decent with modification from ancestral forms)
3. adaptations are often compromises
(Structural reinforcement has been compromised for agility)
4. chance, natural selection, and the environment interact (chance events affect the subsequent evolutionary history of populations) |