Honors Bio Unit 8 Evolution

Descent with modification

All of life is connected by common ancestry

Why is natural selection considered a theory?

It is broader than a hypothesis, generates new hypotheses, and is supported by a large body of evidence

Allopatric speciation

New species form due to geographic barriers splitting populations

Sympatric speciation

When a new species arises within the same geographic area as its parent species

Fossils

The remains of past-living organisms, used to document changes between past and present

Evolutionary tree

- Represents patterns of a descent

- Homologous structures can be used to determine the branching sequence

Example of artificial selection

Dog breeding

The three key points about evolution by natural selection

- Populations evolve, not individuals.

- Evolution has no goal.

- Natural selection depends on time and place.

Stabilizing selection

Favors intermediate phenotypes in natural selection

Directional selection

Favors one extreme phenotype (causes allele frequency to shift in one direction)

Disruptive selection

Favors both extremes in natural selection

Sexual selection

A form of natural selection in which individuals with certain characteristics are more likely to obtain mates than others

Microevolution

Small genetic changes in a population over generations

Hardy-Weinberg equilibrium

States that allele and genotype frequencies will remain constant if:

- A population is large

- Mating is random

- There is no mutation, gene flow, or natural selection

Gene pool

A collection of every type of allele in a population

Relative fitness

The contribution an individual makes to the gene pool of the next generation

How fossils, homologous structures, and vestigial structures provide evidence for evolution

Shows the gradual change of species over time, shared ancestry between different organisms, and the adaptation of traits to new environments

Prezygotic barriers

Prevents fertilization

- Example: Different mating behaviors or times

Postzygotic barriers

Prevents hybrids from being fertile (being able to reproduce)

- Example: mules

Speciation

When one species splits into two or more, increasing diversity

Intrasexual selection vs Intersexual selection

Intra - Competition between individuals of the same sex for mates

Inter - Individuals of one sex choose their mate based on their traits

Polyploidy

Organism has more than 2 complete sets of chromosomes

Biological species concept

The ability of a species to interbreed and produce fertile offspring

Ecological species concept

Defines a species by ecological niches (e.g., fish in different lake zones)

Hybrid zones

Areas where closely related species interbreed and produce hybrids

Adaptive radiation

The evolution of diverse species from a common ancestor

- Driven by isolation, speciation, and recolonization on island chains

Punctuated equilibrium

The hypothesis that evolutionary development is marked by isolated episodes of rapid speciation between long periods of little or no change

Role of reproductive barriers

Serve to isolate the gene pools of species and prevent interbreeding

Habitat differentiation

Populations adapt to different resources (e.g., insects on different plants)

How natural selection, mutation, and genetic drift contribute to microevolution

By altering allele frequencies in a population over time

Macroevolution

Large-scale changes leading to major groups or extinctions (e.g., birds from dinosaurs)

Radiometric dating

Measures the radioactive decay of isotopes

- Can be used to date rocks and fossils, building Earth's timeline

Three domains of life

(Classified by cell type and complexity)

- Prokarya

- Archaea

- Eukarya

Fossil record

Tracks evolutionary history through the sequence in which fossils appear in the rocks

Geologic record

Divides time into eras and periods marked by major events

Mass extinctions

Permian and cretaceous are the most popular; wiped out species and allowed for evolution

Pangea

Supercontinent that affected species distribution

Homoeotic genes

Determine basic features and body plans (e.g., where a pair of legs develop on a fruit fly)

Convergent evolution

Unrelated species develop similar traits in similar environments (e.g., bird and bat wings)

Horizontal gene transfers

Genes transfer between species

- Resulted in the origin of mitochondria

Abiogenesis

The origin of life from non-living matter, such as simple organic compounds.

Panspermia

The hypothesis that life exists throughout the universe and is distributed by celestial bodies.

Oxygen Revolution

A period when cyanobacteria produced oxygen, allowing aerobic respiration to occur.

Anaerobic Respiration

A type of respiration that occurs without free oxygen.

Autotrophs

Organisms that produce their own food, typically via photosynthesis or chemosynthesis.

Gene Flow

The transfer of genetic material between populations, which can affect allele frequencies.

Natural Selection

The process whereby organisms better adapted to their environment tend to survive and produce more offspring.

Gradualism

The idea that changes on Earth occur gradually over long periods of time.

Catastrophism

The theory that the Earth's history has been marked by catastrophic events that cause widespread extinctions.

Homologous Structures

Body parts that share a common embryonic origin but may have different functions.

Analogous Structures

Structures that serve similar functions in different species but do not share a common ancestry.

Vestigial Organs

Body parts that have lost their original function through evolution.

Evolutionary Theory

A well-supported explanation of how species change over time through natural selection and other mechanisms.

Transitional Fossils

Fossils that exhibit traits common to both an ancestral group and its derived descendant group.

Adaptation

A trait that increases the chances of survival and reproduction of an organism.

Divergent Evolution

When two or more related species become more dissimilar over time, often due to differing environmental pressures.

Cultural Evolution

The transmission of knowledge, behaviors, and norms across generations.

Cause of Evolution

Change in environment

Who is Lamarck?

French naturalist best known for his early theory of evolution which proposed the idea of inheritance of acquired characteristics

Who is Charles Darwin?

English naturalist best known for his contributions to the theory of evolution, particularly through the concept of natural selection.

Structural Adaptations

Physical features of an organism that enhance its survival and reproduction in its environment.

Behavioral Adaptations

Actions or behaviors that organisms perform to survive in their environments.

What are physiological adaptations?

Internal body processes that enhance an organism's ability to survive in its environment.

Bottleneck effect

A sharp reduction in the size of a population due to environmental events or human activities, leading to a loss of genetic diversity.

Founder Effect

A genetic drift that occurs when a small group of individuals establishes a new population, leading to reduced genetic diversity and different allele frequencies compared to the original population.

Cladogram

Diagram that shows the evolutionary relationships among various biological species based on shared characteristics.

Phylogenetic Tree

Branching diagram that represents the evolutionary history of a group of organisms based on genetics, illustrating how they are related through common ancestry.

Paraphyly

Group of organisms that includes a common ancestor but does not include all of its descendants.

Polyphyly

Grouping of organisms that do not share a recent common ancestor, often including members from different lineages.

Monophyly

Group of organisms that includes a common ancestor and all of its descendants, representing a complete branch on the tree of life.