Bio lec 13

Mayapple (Podophyllum peltatum)

A woodland plant found in eastern North America that grows in colonies and contains the toxin Podophyllotoxin in all parts except the fruit, which is edible and has a taste like pineapple.

Evolution by Natural Selection

A theory developed by Charles Darwin suggesting that species evolve over time through a process where individuals with advantageous traits are more likely to survive and reproduce.

H.M.S. Beagle

The ship on which Charles Darwin served as a naturalist during its voyage around the world from 1831 to 1836.

Uniformitarianism

A geological principle proposed by Charles Lyell suggesting that the same gradual processes that operate today also operated in the past, implying that the Earth is very old.

Natural Selection

The process by which individuals with favorable traits are more likely to survive and reproduce, leading to changes in the traits of populations over generations.

Descent with Modification

Darwin's concept that each generation of organisms is genetically modified by environmental interactions.

Microevolution

Evolution occurring at the smallest scale, which involves changes in allele frequencies in a population over time.

Hardy-Weinberg Equilibrium

A theoretical state in which a population's allele frequencies remain constant over time, requiring specific conditions that are rarely met in nature.

Genetic Drift

A random change in allele frequencies in a population, particularly significant in small populations, which can lead to a loss of genetic diversity.

Sexual Selection

A form of natural selection where individuals compete for mates, influencing traits based on reproductive success.

Homologous Structures

Body parts in different species that share a similar ancestral origin but have evolved to serve different functions, indicating common ancestry.

Fossil Record

The preserved remains or impressions of past organisms that provide evidence of evolution by showing changes in species over time.

Gene Flow

The transfer of genetic material between populations, which can introduce new alleles and increase genetic diversity.

Directional Selection

A type of natural selection that favors phenotypes at one extreme end of a phenotypic range.

Stabilizing Selection

A type of natural selection that favors intermediate phenotypes and selects against extremes.

Diversifying Selection

A type of natural selection that favors phenotypes at both extremes of a range, potentially leading to speciation.

Methicillin-resistant Staphylococcus aureus (MRSA)

An example of modern antibiotic resistance illustrating the principles of evolution by natural selection.