Apes Ch 4

Biological diversity/ biodiversity

the variety of the earth's species, or varying life-forms, the genes they contain, the ecosystems in which they live, and the eco- system processes of energy flow and nutrient cycling that sustain all life


a set of individuals that can mate and pro- duce fertile offspring.


large regions such as forests, deserts, and grasslands with distinct climates and certain species (especially vegetation) adapted to them.


mineralized or petrified replicas of skeletons,
bones, teeth, shells, leaves, and seeds, or impressions of such items found in rocks

biological evolution (or simply evolution)

the process whereby earth's life changes over time through changes in the genetic characteristics of populations

theory of evolution

all species descended from earlier, ancestral species. life comes from life.

natural selection

individuals with certain traits are more likely to survive
and reproduce under a particular set of environmen- tal conditions than are those without the traits


random changes in the DNA molecules

adaptation, or adaptive trait

any heritable trait that improves the ability of an individual organism to survive and to reproduce at a higher rate than other individuals in a population are able to do under prevailing environmental conditions.

differential reproduction

enables individuals with the adaptive trait to produce more surviving offspring than other members of the population produce.

Genetic resistance

the ability of one or more organisms in a population to tolerate a chemical designed to kill it.

summary of process of biological evolution by natural selection

Genes mutate, individuals
are selected, and populations evolve such that they are better adapted to survive and reproduce under existing environmental conditions

How Did Humans Become Such a Powerful Species?

strong opposable thumbs, ability to walk upright, complex brain


one species splits into two or more different

Geographic isolation

when different groups of the same population of a species become physically isolated from one another for a long period of time

reproductive isolation

mutation and change by natural selection operate independently in the gene pools of geographically isolated populations


process in which an entire species ceases to exist

endemic species

Species that are found in only one area and are therefore especially vulnerable to extinction.

background extinction

Low rate at which species have disappeared throughout most of the earth's long history

mass extinction

a significant rise in extinction rates above the background level

species diversity

the number and variety of species it contains.

species richness

number of different species present, important component of species diversity

species evenness

the comparative num- bers of individuals of each species present, component of species diversity

What effects does species richness have on an ecosys- tem?First, is plant productivity higher in species-rich ecosystems? Second, does species richness enhance the stability, or sustainability, of an ecosystem?

Research sug- gests that the answers to both questions may be yes, but more research is needed before these scientific hypoth- eses can be accepted as scientific theories.

important principle of ecology

each species has a specific role to play in the ecosystems where it is found

ecological niche

role that a species plays in its ecosystem

Generalist species

Species that have broad niches.They can live in many different places, eat a variety of foods, and often tolerate a wide range of environmental condi- tions. Flies, cockroaches, mice, rats, white-tailed deer, raccoons, and humans are gen- eralist species.

specialist species

Species that occupy narrow niches. They may be able to live in only one type of habitat, use just one or only a few types of food, or tolerate a narrow range of cli- matic and other environmental conditions

Is it better to be a generalist or a specialist?

When environmental conditions are fairly constant, as in a tropical rain forest, specialists have an advantage because they have fewer competitors. But under rapidly changing environmental conditions, the generalist usually is better off than the specialist.

Native species

those species that normally live and thrive in a particular ecosystem.

nonnative species

also referred to as invasive, alien, and exotic species. species that migrate into, or are deliberately or accidentally intro- duced into, an ecosystem

indicator species

Species that provide early warnings of damage to a com- munity or an ecosystem

Keystone species

species whose roles have a large effect on the types and abundance of other species in an ecosystem. pollinators, top predators

foundation species,

species that play a major role in shaping their communities by creating and enhanc- ing their habitats in ways that benefit other species. For example, elephants push over, break, or uproot trees, creating openings in the grasslands and woodlands of Africa. Beavers act as "ecological engineers," building dams in streams to create ponds and wetlands