Unit 7 bio concept check

Natural selection

Process where organisms with traits better suited to their environment survive and reproduce more successfully Example: bacteria surviving antibiotics and passing resistance to offspring

Artificial selection

Process where humans selectively breed organisms for desired traits Example: breeding dogs for size or behavior traits

Population genetics

Study of how allele frequencies change in populations over time due to evolutionary forces Example: tracking how a gene becomes more common in a population over generations

Genetic variation

Differences in DNA among individuals within a population that can be inherited Example: different eye colors within a group of humans

Allele frequency change

Shift in how common certain gene versions are in a population over time Example: increase in antibiotic-resistant bacteria genes

Hardy-Weinberg equilibrium

Condition where allele frequencies in a population stay constant unless evolutionary forces act on them Example: theoretical population with no mutation or selection

Conditions of equilibrium

Requirements include no mutation, random mating, no natural selection, very large population, and no migration Example: idealized population with no outside influence

Random occurrence in evolution

Unpredictable events that change allele frequencies without regard to fitness Example: natural disaster randomly killing individuals regardless of traits

Genetic drift

Random change in allele frequencies in small populations over time Example: certain traits becoming common just by chance

Bottleneck effect

Sharp reduction in population size leading to reduced genetic variation Example: survivors of a disaster repopulating a species

Founder effect

New population formed by a small group carrying limited genetic variation Example: isolated island population started by a few individuals

Gene flow

Movement of genes between populations through migration and reproduction Example: pollen spreading between plant populations

Evidence of evolution

Multiple scientific sources showing species change over time and share common ancestry Example: similarities between fossils and modern species

Fossil record

Preserved remains or traces of organisms that show changes over time Example: transitional fossils showing gradual changes in species

Homologous structures

Body parts with similar underlying structure due to shared ancestry but different functions Example: human arm and whale flipper

Vestigial structures

Reduced or unused structures inherited from ancestors Example: human tailbone

Molecular similarities

Similarities in DNA or protein sequences that show evolutionary relationships Example: humans and chimpanzees sharing similar DNA sequences

Biogeography

Study of how species are distributed across geographic locations due to evolution and history Example: unique species found on islands

Ongoing evolution

Current observable changes in species due to environmental pressures Example: increasing antibiotic resistance in bacteria

Antibiotic resistance

Evolution of bacteria that survive drug treatment Example: bacteria no longer killed by common antibiotics

Pesticide resistance

Insects evolving resistance to chemicals used to kill them Example: mosquitoes surviving insecticides

Pathogen evolution

Changes in disease-causing organisms over time to survive hosts or treatments Example: viruses mutating to evade immune systems

Common ancestry

Idea that all organisms share ancestors from which they evolved over time Example: all mammals sharing a distant ancestor

Speciation

Process where new species form due to reproductive isolation Example: populations of a species becoming unable to interbreed

Reproductive isolation

Conditions that prevent populations from interbreeding successfully Example: different mating behaviors or timing

Pre-zygotic isolation

Barriers that prevent fertilization from occurring Example: species mating at different times of year

Post-zygotic isolation

Barriers that occur after fertilization leading to nonviable or infertile offspring Example: mule being sterile

Allopatric speciation

Speciation caused by geographic separation of populations Example: animals separated by a mountain range evolving differently

Sympatric speciation

Speciation without geographic separation, often due to behavioral or genetic differences Example: insects evolving into separate species in same area

Convergent evolution

Process where unrelated species develop similar traits due to similar environments Example: birds and bats both evolving wings

Punctuated equilibrium

Evolution pattern with long periods of stability interrupted by rapid change Example: sudden appearance of new species in fossil record

Gradualism

Evolution pattern where changes occur slowly and continuously over time Example: slow transformation of species over millions of years

Phylogenetic tree

Diagram showing evolutionary relationships among species based on common ancestry Example: branching diagram of mammals and reptiles

Cladogram

Diagram that shows relationships based on shared traits rather than time Example: grouping species by shared derived characteristics

Extinction

Permanent disappearance of a species from Earth Example: dinosaurs no longer existing

Origin of life

Scientific study of how life first began from non-living matter Example: early Earth chemical reactions forming simple cells

RNA world hypothesis

Idea that RNA was the first genetic material capable of storing information and catalyzing reactions Example: RNA acting before DNA and proteins existed