Evolution Chapter 15

Two schools of thought  Creation – God worshipping people  Evolution – atheist

Evolution Evolution – a change in an organism over a long period of time Charles Darwin – the father of evolution  Darwin had some proof to support his theory The shape of fossils Darwin’s time on the HMS Beagle Darwin’s trip to the Galapagos Islands  Located off of South America  Galapagos tortoises and Galapagos finches are endemic species

Evolution Galapagos tortoises

Evolution Galapagos finches

Artificial Selection Artificial selection – breeding organisms with specific traits in order to produce offspring with identical traits  Man chooses which traits organisms should have Example – dogs and cows

Artificial Selection  Example – beef cows vs. dairy cows Holstein Angus

Natural Selection Natural selection – occurs when organisms with favorable variations survive, reproduce, and pass their variations to the next generation  Selection occurs on its own or “naturally” Example – birds with long tail feathers

Natural Selection Darwin called natural selection “survival of the fittest”  Stronger organisms with preferred traits lived and made fertile offspring  Example – Two populations of fish One population is faster than the other Natural selection would favor which population? “X” indicates faster swimmer

Natural Selection Natural selection would favor polar bears in the arctic and grizzly bears in the taiga.  Why?

Adaptations: Evidence for Evolution Adaptation – any variation that aids an organism’s chances of survival in its environment Adaptations in species develop over many generations Adaptations of a frog

Adaptations: Evidence for Evolution Several forms of adaptations:  Mimicry – a structural adaptation that enables one species to resemble another species

Adaptations: Evidence for Evolution  Aggressive mimicry – a technique used by some animals to lure prey to them by mimicking something else Angler fish

Adaptations: Evidence for Evolution  Aggressive mimicry Golden orb weaver will weave heavy zig-zag lines of web to attract insects  Found in Australia

Adaptations: Evidence for Evolution  Aggressive mimicry Snapping turtle’s tongue resembles a worm

Adaptations: Evidence for Evolution  Camouflage – an adaptation that enables species to blend with their surroundings

Adaptations: Evidence for Evolution  Warning coloration – A protection adaptation used by some animals that uses color to warn other animals to keep away Yellow jacket Poison dart frog

Other Evidence for Evolution Anatomy  Homologous structures – structures with common evolutionary origins Provides evidence of evolution from a common ancestor Examples: forelimbs of lizards, whales, humans, and birds

Other Evidence for Evolution Analogous structures – structures that do not have a common evolutionary origin but are similar in function

Other Evidence for Evolution Insect Pterodactyl Bat Bird Analogous structures

Other Evidence for Evolution Vestigial structure – a structure in a present- day organism that no longer serves its natural purpose, but was probably useful to an ancestor  Example: appendix  Ex. – pythons have vestigial hindlimbs

Other Evidence for Evolution Embryology – the earliest stage of growth and development of both plants and animals

Population Genetics and Evolution Evolution occurs on populations, not individuals Variation coupled with natural selection fuels evolution Gene pool – all of the alleles in a population’s genes

Population Genetics and Evolution Natural selection acts on variations  Stabilizing selection –favors average individuals in a population  Directional selection – favors one of the extreme variations of a trait  Disruptive selection – individuals with either extreme of a trait’s variation are selected for Tends to eliminate intermediate phenotypes

The Evolution of Species Speciation – the evolution of a new species Several ways for speciation to occur:  Geographical isolation – a physical barrier divides a population

The Evolution of Species  Reproduction isolation – formerly interbreeding organisms can no longer mate and produce fertile offspring

Patterns of Evolution Adaptive radiation (divergent evolution) – an ancestral species evolves into an array of species to fit a number of diverse habitats Laysan finches from the Hawaiian islands

Patterns of Evolution Convergent evolution – occurs when unrelated species evolve similar traits