Biology and Evolution: Rocks, Biodiversity, and Phylogeny

Rock vs mineral

A mineral has a definite chemical formula and crystal structure; a rock is made of one or more minerals.

How to tell if a rock formed underground

Large crystals = underground (intrusive); small/no crystals = surface (extrusive).

Foliation

Alignment of minerals in metamorphic rock due to pressure.

Shale

A sedimentary rock formed from compacted mud/clay.

Three ways rocks become metamorphic

Heat, pressure, hot fluids.

Sexual reproduction required for natural selection?

No — natural selection occurs in asexual organisms too.

Alfred Russel Wallace

Developed natural selection independently of Darwin.

Darwin and pigeons

He bred pigeons to study variation and selection.

Why Lamarck was wrong

Acquired traits are not inherited; only genetic traits are passed on.

Empirical evolutionary methods

Data, statistics, comparisons, experiments.

Theoretical evolutionary methods

Models, equations, predictions.

IUCN categories

Vulnerable, Endangered, Critically Endangered, Extinct.

Instrumental value of biodiversity

Value based on usefulness to humans.

Why low genetic diversity is a problem

Low adaptability and high disease risk.

Two strategies for low-diversity species

Genetic rescue; captive breeding and reintroduction.

Five Galápagos environment factors

Equator sun, cold currents, volcanic soils, isolation, microclimates.

Hemimetabolous development

Nymph → adult; no pupa; faster but more competition.

Holometabolous development

Larva → pupa → adult; less competition; vulnerable pupa.

Giraffe recurrent laryngeal nerve

Developmental constraint inherited from fish ancestors.

Main assumption in phylogeny

Similarity and homology guide tree construction.

CCR5-Δ32 mutation

Inhibits HIV by disabling CCR5 coreceptor.

CCR5-Δ32 homozygous phenotype

Highly resistant to HIV.

Outgroup use in phylogeny

Helps root the tree and resolve polytomies.

Number of unrooted trees with 3 taxa

One.

Precambrian

Oldest eon.

Current era

Cenozoic.

Symplesiomorphy

Shared ancestral trait.

Synapomorphy

Shared derived trait.

Convergent evolution

Independent evolution of similar traits.