5.1 and 5.2 Evolution and Community Ecology

Genetic drift

Evolution that occurs by chance Ex: Birds only eating green beetles, overtime there will be less green and there will be more brown beetles and overtime the brown beetles will become prominent.

Predator-prey relationship

Examples of coevolution, the process by which two species evolve in response to changes in each other.

Ecological Niche

Functional position of an organism in its environment (organisms role)

Speciation

How new species are generated --> results in every form of life on Earth today and in the past

Realized Niche

Niche that is actually occupied. It is narrower than the fundamental niche. ACTUAL (real world)

Examples of Mutualistic Relationships

Oxpeckers and zebra, Cape buffalo, and rhinoceros

Resource partitioning

Reduces competition among species (caused from Niche partitioning)

Artificial Selection

Selection under human direction --> human directed & have bred animals and plants with beneficial traits

Competition

The active demand between two or more organisms for a resource

Biological evolution

The change in a population's gene pool over time

Natural Selection

Traits are useful for survival and reproduction are passed on more frequently than those that are not

Gause's Principle

Two or more resource-limited species, having identical patterns of resource use, cannot coexist in a stable environment: one species will be better adapted and will out-compete or otherwise eliminate the other(s)". If two species compete for some of the same resources (e.g. food items of a particular size), their resource use curves will overlap. In the zone of overlap, interspecific competition is the most intense.

Interspecific competition

Usually less intense than intraspecific competition because niche overlap between species is not complete.

Predation

When a predator hunts, kills, and consumes prey. Causes cycles in predatory and prey population sizes (connected)

When does extinction occur?

When environmental conditions change more rapidly than the species can adapt

Niche partitioning

When roles are divided up Ex: tree & birds - one type gets top, one gets bottom, not that much overlap but still some competition LEADS TO Resource partitioning

Microhabitats

When species with similar ecological requirements may reduce competition by exploiting different ones of these within the ecosystem. Example: Ecologically similar damsel fish at Heron Island, Queensland, Australia exploit different resources or regions over the coral reef.

Commensalism

a relationship in which one species benefits while the other is unaffected (Ex: Shark, remora) ; not many relationships like this, rare

Mutualism

a relationship in which two or more species benefit

Traits of defense

as camouflage, mimicry, and warning coloration have evolved in response to predator-prey interactions. Ex: warning - brightly colored —> poison

Geographic Isolation

causes a species to become different species Ex: Squirrels in Grand Canyon - each region has its own squirrel

Ectoparasites

live externally, Ex: tick

Endoparasites

live within host's body, Ex: tapeworm

Parasite

lives in or on a host organism —> host is always harmed but it is not usually killed (Positive & Negative - host is negative)

Commensal Relationships

one party (the commensal) benefits, while the host is unaffected.

Fundamental Niche

the full range of environmental conditions (biological and physical) under which the organism can exist. IDEALIZED

Types of Selection (know graphs - slide 13 on ppt)

1. Stabilizing selection - average 2. Directional selection - shifting towards one extreme 3. Disruptive selection - both extremes

How many known mass extinctions are there?

5 - the 6th is Human catastrophe

Allopatric Speciation

(most important ways) through geographic isolation

2 types of Ecological Niches

1. Generalists - survive in a wide range of areas 2. Specialist - narrow niche & can't adapt as easily (have specific requirements) ex: Koala Bear, Pandas

Conditions of Natural Selection

1. Organisms produce more offspring than can survive. Ex: insects and fish; lots of babies 2. Individuals vary in characteristics, some of which are heritable. Ex: Diversity and overall health of a population; diversity 3. Individuals vary in fitness or reproductive success; have passable genes and can reproduce

Gene

A sequence of DNA that codes for a particular trait

Mutation

Accidental change in DNA that can give rise to variation among individuals

Epiphytes

Air plants, ex: Bromeliads orchids, gain access to a better position in the forest canopy, with more light for photosynthesis, but do no harm to the host tree.

Gene pool

All the genes present in a population

Obligate Mutualism

Between a fungus and either a green alga or a cynobacterium

Interspecific * ON QUIZ

Between individuals of DIFFERENT species

Intraspecific (ON QUIZ)

Between individuals of the SAME species (mate)

Extinction

Disappearance of species from Earth; generally occurs gradually; one species at a time

Migration (gene flow)

Movement of individuals into (immigration) or out of (emigration) a population

Background extinction

Naturally occurring extinction in nature

Habitat, activity pattern (nocturnal, diurnal), resources

Niche comprises of ____, _____, _____