units 1 & 2 Flashcards
Natural Selection
*Darwin
-a mechanism that can lead to adaptive evolution
-differences in the phenotypes of individuals cause some of them to survive and reproduce more effectively than others
Descent with modification
*Darwin
the passing of traits from parents to offspring
-over time this process could account for gradual change in species traits and homology
**way to classify species
Homology
similarity of characteristics resulting from shared ancestry
Homologous characteristic
similar in two or more species because it is inherited from a common ancestor
Mary Anning
paleontologist that discovered jurassic marine fossil beds in England
How do mutations lead to evolutionary change?
creates a new DNA sequences for a particular gene thus creating a new allele
Convergent Evolution
occurs when species occupy similar ecological niches and adapt in similar ways in response to selective pressures
*these adaptive traits are known as analogous structures (homologous structures have a common origin)
Horizontal Gene Transfer
the movement of genetic information between organisms, the spread of antibiotic resistances genes among bacteria which fuels pathogen evolution
Synapomorphy
-occurs when populations are in the same geographic area
-derived form of a trait that is shared by a group of related species
Artificial selection
-the selective breeding of animals and plants to encourage the occurrence of desirable traits
-individuals with preferred characteristics are mated or cross pollinated with other individuals having similar traits
Zoonosis
a disease which can be transmitted to humans from animals
Viral reassortment
occurs when genetic material from different strains is mixed into new combinations with a single cell
Jean-Baptiste Lamarck
-an expert on plants and invertebrates
-found anatomical similarities between species
**living things evolved in a continuously upward direction
Charles Darwin and the Origin of Species
-naturalist best known for natural selection
-species can change over time, new species come from preexisting species and all species share a common ancestor
Tetrapod evolution and divergence
-a vertebrate with 4 limbs (descended from snakes, now mammals, birds, reptiles)
Homoplasy
a character state similarity NOT due to shared descent
EX: convergent evolution
How does meiosis generate genetic variation?
During meiosis, homologous chromosomes (1 from each parent) pair along their lengths and cross over then trade some of their genes
*recombination results in genetic variation
Phenotypic plasticity
the ability of individual genotypes to produce different phenotypes when exposed to difference environmental conditions
Antagonistic pleiotropy
the condition that occurs when a mutation with beneficial effects for one trait also causes detrimental effects on other traits
Genetic Bottleneck
an event in which the number of individuals in a population is reduced drastically
*even if temporary, it has lasting effect on genetic variation of a population
Founder Effect
*form of genetic drift
-the loss of allelic variation that accompanies the founding of a new population from a very small number of individuals
-this effect can cause the new population to differ considerably from the OG population
Negative Frequency-Dependent Selection
takes place when rare genotypes have higher fitness than common genotypes
*can maintain genetic variation within populations
Heterozygote Advantage
when selection favors heterozygote individuals over either the dominant homozygote or the recessive homozygote
Inbreeding depression
a reduction in the average fitness of inbred individuals relative to that of outbred individuals
-arises because rare recessive alleles become expressed in a homozygous state where they can affect the performance of individuals
Phenotypic variation is the ___
direct consequence of genetic variation
-acts with environment and beahvior
Reaction norm
pattern of phenotypic expression of a single genotype across a range of environments
*depict how development maps the genotype into phenotype as a function of the environment
Broad sense heritability
(H^2)
the proportion of the total phenotypic variance of a trait that is attributed to genetic variance
*look at equation
Narrow sense heritability
(h^2)
proportion of the total phenotypic variance attributed to the additive effects of alleles
Genetic linkage
genes that are close together on a chromosome that tend to “stick together”
Selective sweep
when a new advantageous mutation eliminates or reduces variation in linked neutral sites as it increases in frequency in the population
*also genetic hitchhiking
Preexisting sensory bias
female mating preferences for male traits
Marie Curie
chemist who conducted research on radioactivity
-first woman to win a Nobel Prize twice!
Ring Species
two populations do not interbreed that are living in the same region and connected by geographic ring of populations that can interbreed
EX: salamanders of Cali
