Biology Exam

Proximate Causes

Explains how a behavior happens in the moment (mechanism)

Ultimate Causes

Explains why someone has evolved (evolutionary factor)

Cost Benefit Balance

Natural selection favors action where the benefits outweigh the costs

Measuring Population Density

Population Density = # of population / land area

Demography (Define)

The statistical study of human populations

Demography (What It Tells Us)

How populations change in size and composition by measuring births, deaths, and migration

Fecundity (Life Tables)

A life table summarizes how survival and reproduction fluctuate across different age intervals

Fecundity (Survivorship Curves)

Primarily graph the proportion of survivors over time, fecundity dicates the species life history strategy and evolution trade offs

Competition (Limit Population & Carrying Capacity)

As populations grow, individuals must compete for limited food, water, and shelter.

Predation (Limit Population & Carrying Capacity)

High population densities make prey more visible and accessible, attracting more predators

Disease & Parasites (Limit Population & Carrying Capacity)

Communicable diseases spread much faster in dense, crowded populations

Waste Accumulation (Limit Population & Carrying Capacity)

High population densities can cause a buildup of toxic waste, which reduces survival rates

Population Cycles

Predictable, repeating rises and falls in the size of a species population over a specific period of time

Metapopulations from Habitat Fragmentation

When a once-continuous, single population is broken into a network of spatially separated, smaller sub populations

Age Structure of Human Populations

It is primarily driven by three interconnected factors: birth rates (fertility), death rates (mortality and life expectancy), and migration

Assessing Extinction Risk (Population Data and Ecological Diversity)

Estimates the population’s long-term survival and helping to pinpoint at risk species before it’s too late

Guiding Habitat Protection (Population Data and Ecological Diversity)

Uses spatial population data to build roads and developments while minimizing habitat fragmentation

Monitoring Genetic Diversity (Population Data & Ecological Diversity)

Uses effective population size to help maintain evolutionary resilience and guards against inbreeding

Managing Sustainable Harvesting (Population Data & Ecological Diversity)

Uses science-based harvest limits to prevent overhunting and overharvesting to maintain the natural carrying capacity

Commensalism (Species Interactions)

One species benefit and one is completely unaffected

Competition (Species Interactions)

Both are harmed due to shared, limited resources

Consumption (Species Interactions)

One benefits by eating or absorbing nutrients from the other

Mutualism (Species Interactions)

Both species benefit from the relationship

Interpreting Life Tables

1.Find your Age (x) in the first column

2.Trace to the Number Surviving (lx) column to see how many people out of 100,000 made it to your age.

3.Trace to the Life Expectancy (ex) column to find your remaining years of life

Type 1 Curve (Survival Curves)

Invest heavily in few offspring & provide extensive parental cares to ensure survival (K-selected)

Type 2 Curve (Survival Curves)

Produce moderate amounts of offspring and provide some level of parental care

Type 3 Curve (Survival Curves)

Maximize reproductive success by producing massive quantities of offspring and invest little to no time (r-selected)