Ecology Exam 1

What is the fundamental paradigm of modern biology regarding evolution?

Modern organisms are modified descendants of previous species, all species are related through common ancestors, and species adapt to their environments via natural selection.

Define natural selection.

Natural selection is the disproportionate reproduction of genetic varieties best suited to their ecological situation.

What is ecology?

Ecology studies the interactions of organisms with their physical and biological environments.

Name and briefly describe the five main areas of ecology.

Autecology: Study of adaptations of individual organisms to their environment.

Population ecology: Study of species distribution, abundance, and influencing factors.

Community ecology: Study of species co-existence, changes in number and composition over time.

Ecosystem ecology: Study of community interactions with the physical environment, energy flow, and nutrient cycling.

Conservation biology: Study of biodiversity, threats, and preservation strategies.

Outline key events in the early history of Earth relevant to evolutionary biology.

Big Bang (~13.8 BYA)

Milky Way formation (~13.6 BYA)

Solar System formation (~4.5 BYA) from interstellar cloud

Earth formed in the Goldilocks Zone allowing liquid water

Hadean Eon (4.5-3.8 BYA): Earth condensation, moon formation, ocean formation

Archean Eon (3.8-2.5 BYA): Continental plates formed, Earth’s magnetic field established, origin of life

Proterozoic Eon (2.5-0.54 BYA): Evolution of photosynthesis, Oxygen Catastrophe, snowball earth

Phanerozoic Eon (542 MYA-present): Complex multicellular life, land invasion, mass extinctions, emergence of humans

What is the significance of the Oxygen Catastrophe?

It caused massive extinction of anaerobic life, triggered global glaciation (Snowball Earth), led to ozone layer formation, and enabled complex eukaryotic life.

What is plate tectonics and how does it impact ecology and evolution?

Plate tectonics is the expansion and contraction of Earth’s crust that creates mountains, volcanoes, and causes continental drift like the breakup of Pangaea, affecting habitats and species distribution.

What percentage of Earth's surface energy comes from solar radiation?

99.98% of energy inputs come from solar radiation; the rest from radioactive decay and tidal energy.

Describe the greenhouse effect and its consequences.

Solar radiation mostly passes through the atmosphere and is absorbed by Earth’s surface. Earth emits infrared radiation, which greenhouse gases absorb and re-emit mostly back to the surface, warming the Earth and moderating temperature extremes.

List greenhouse gases by their global warming potential from least to greatest.

Water vapor < CO2 < Methane < N2O < CFCs.

What environmental effects result from the rise in greenhouse gases?

Ocean warming, ice sheet and glacier melting, permafrost thaw, rising sea levels, extreme weather events, and changes in temperature and rainfall patterns.

What is albedo, and how does it vary among surfaces?

Albedo is the reflection of sunlight; varies as follows: Clouds (10-90%), Sea ice (50-90%), Snow (80-95%), Water (10-60%), Forest (10-20%), Grassland (10-25%), Asphalt (5-10%).

Why are poles colder than the equator?

Poles receive less solar radiation because light passes through more atmosphere layers at an angle, reducing intensity, and receive 40% less solar radiation than equator.

Explain the role of Hadley cells in Earth’s atmospheric circulation.

Warm tropical air rises at the Intertropical Convergence Zone (0°), cools and rains, then dry air sinks around 30° N/S, warming and flowing back toward the equator creating trade winds.

What is the Coriolis effect and how does it influence wind patterns?

It causes deflection of moving air and water due to Earth’s rotation, shaping prevailing wind directions such as trade winds and westerlies.

Differentiate El Niño and La Niña.

El Niño features warmer ocean surface temperatures and weakened trade winds; La Niña has cooler surface temperatures and strengthened trade winds.

Describe how altitude and topography influence climate.

Higher altitudes have thinner air and different life zones; rain shadows cause one side of mountains to be wet and the other dry; north/south-facing slopes have temperature differences; valley air traps pollutants; canopy effects cool and reduce wind.

Contrast maritime temperature with continental temperature regimes.

Maritime climates have moderated temperatures due to ocean influence and sea breezes, with less day-night temperature variation; continental climates have greater extremes due to lack of such moderating influences.

What were the key evolutionary concepts presented by Darwin and Wallace?

Descent with modification, common ancestry, gradualism, speciation by natural selection, and sexual selection.

Describe Darwin’s logic behind natural selection.

High fertility potential, population stability, limited resources lead to struggle; there is heritable variability; unequal survival causes natural selection; leading to gradual population change.

What is Wallace’s Line?

A biogeographic boundary between Borneo and New Guinea that separates species with Asian and Australasian affinities.

Enumerate Darwin’s six key theories.

Evolution (descent with modification)

Common ancestry (tree of life, LUCA)

Gradualism (small-step changes)

Speciation (origin of new species)

Natural selection (mutation plus differential reproduction)

Sexual selection (traits for mating success)

What post-Darwinian advances have contributed to evolutionary theory?

Mendelian genetics and the Modern Synthesis, molecular biology, plate tectonics, selfish gene theory, neutral evolution and molecular clocks, cladistic taxonomy, evolutionary developmental biology (Evo-Devo), and human evolution studies.

How did natural theology view adaptation before Darwin?

Species were created perfectly by God with fixed places in a Great Chain of Being; complexity implied an intelligent designer.

What was Paley’s "watchmaker argument"?

Complexity and purposeful design in the universe imply an intelligent designer, analogous to a watch requiring a watchmaker.

How does classification reflect evolutionary relationships?

Organisms are grouped hierarchically (kingdom to species), with shared traits (plesiomorphies) reflecting common ancestry; Darwin’s “Tree of Life” explains these trait groupings through descent.

What is biogeography and how does evolution explain it?

The geographic distribution of species is shaped by dispersal (colonization) and vicariance (geographic separation), explaining patterns of related but distinct species in isolated areas.

Describe the fossilization process.

Organism dies near water, soft tissues decomposed or scavenged, bones covered by sediment, sediments fossilize organic material, and erosion later exposes fossils.

Differentiate types of fossils.

Intact fossils (organic material preserved), compression fossils (smeared organic material), cast fossils (molds), permineralized fossils (organic replaced by minerals), trace fossils (tracks), microfossils (small organisms).

How are fossils dated?

Relatively by geological strata and absolutely by radiometric dating (e.g., potassium-40); molecular clocks compare genetic divergence.

Name important transitional fossils and their significance.

Ambulocetus natans (walking whale ancestor), Archaeopteryx (bird-reptile transition) showing evolutionary links between major groups.

What is the Sarawak Law?

Every species comes into existence in close spatial and temporal coincidence with a pre-existing related species.

What is the comparative method in evolutionary biology?

Comparing living and extinct species to infer relationships, ancestral traits, trait changes, and intermediate stages of complex features.

Define homologies and give examples.

Shared traits from common ancestry, which can appear different due to divergent evolution; e.g., tetrapod forelimbs with the same wrist bones but different functions.

Define analogies and how they differ from homologies.

Similar traits that evolved independently due to convergent evolution and not common ancestry; e.g., hummingbird wings and hummingbird moth wings.

What are vestigial structures?

Reduced or underdeveloped structures that were functional in ancestors but serve minimal or different roles now; e.g., whale hind limbs, ostrich wings.

What are pseudogenes?

Non-functional genes that once were functional, often remnants of evolutionary history; e.g., frequent OR (olfactory receptor) gene pseudogenes in humans.

How can the argument from "perfect traits" be refuted?

Complex traits often have intermediate stages serving other functions, evolving gradually; no trait is perfectly optimal as there are trade-offs and evolutionary constraints.

What mechanisms drive genome growth in evolution?

Gene duplication (splitting) and mutations, some of which create novel gene functions while others become pseudogenes.

How is ongoing evolution observed today?

Observing genetic and phenotypic changes in contemporary species and documentation of new speci