Ground Rules for Behavioral Ecology What biological concepts and terms you need to remember and understand in order to make the field of Behavioral Ecology

Ground Rules for Behavioral Ecology

What biological concepts and terms you need to remember and understand in order to make the field of Behavioral Ecology make sense…

Genetic Traits– Organisms are what they are, because of their DNA– The DNA is sequenced in such a way that chains of Amino Acids

are built (in a specific order) and produce proteins. The combinations of proteins produce everything that the organism is made of, and control the behavior of the organism.

– The different items that the DNA codes for are known as traits and can be physical (eg. the color of eyes or the shape of leaves), or they can be behavioral (eg. Salmon returning to the stream where they were born to spawn).

– In truth, organisms are also a product of their environment, so in all organisms do, genetics is responsible (in part) and environmental conditions are responsible (in part).

– The process of changing genetic traits is known as Evolution.– Evolution requires three conditions to occur

• There must be an environmental pressure put on the organisms to adapt to conditions that are present.

• There must be a spontaneous mutation of some kind (mistake in the DNA sequence code)– Can be caused by Mutagens (chemicals, high energy radiation, etc.)– Can be caused by DNA recombination errors (pieces sticking that shouldn’t)

• The mutation must be beneficial to the organism that has it and make that organism better adapted to over come the environmental pressure and produce offspring that show recruitment.

– Recruitment is when the offspring of individuals have offspring.– Sometimes Evolution takes place in a group of reproductively

isolated individuals, and that is when speciation takes place (new species are evolved).

Evolution

Head of a normal fruit fly

Antenna

Eye

Head of a developmental mutant

Leg

Working independently but at the same time Charles Darwin and Alfred Russel Wallace developed what has come to be known as “The Theory of Evolution”.

This theory states that the primary mechanism of evolutionary change, producing adaptation of organisms to their environment, is natural selection, which involves the differential survival and reproduction of individuals within a population.

In other words, Survival of the Fittest (if your definition of Fitness means the ability to produce young that exhibit recruitment.)

The better able you are to produce young, the more your genes will spread.

Copyright © 2009 Pearson Education, Inc.

Evolution cont’d

• Note these important points – Individuals do not evolve: populations evolve– Natural selection can amplify or diminish only heritable

traits; acquired characteristics cannot be passed on to offspring

– Evolution is not goal directed and does not lead to perfection; favorable traits vary as environments change

– Will natural selection act on variation in hair style in a human population?


Natural Selection as the mechanism for Evolution

Terminalbud

Lateralbuds

Leaves

Kale

Stem

Brussels sprouts

Cauliflower

Cabbage

Kohlrabi

Wild mustard

Flowerclusters

Flowersand stems

Broccoli

Rosemary and Peter Grant have worked on Darwin’s finches in the Galápagos for over 20 years

– In wet years, small seeds are more abundant and small beaks are favored

– In dry years, large strong beaks are favored because large seeds remain


Natural Selection in Action

A gene pool is the total collection of genes in a population at any one time

Microevolution is a change in the relative frequencies of alleles in a gene pool over time


Populations are the units of evolution

The three main causes of evolutionary change are

– Natural selection

– Genetic drift

– Gene flow


Three Causes of Evolutionary Change

– Genetic drift is a change in the gene pool of a population due to chance

– In a small population, chance events may lead to the loss of genetic diversity

– Genetic drift produces the founder effect when a few individuals colonize a new habitat

– The bottleneck effect leads to a loss of genetic diversity when a population is greatly reduced

– Favorite Example…


Genetic Drift

– Gene flow is the movement of individuals or gametes/spores between populations and can alter allele frequencies in a population


Gene flow

Originalpopulation

Fre

qu

en

cy o

fin

div

idu

als

Originalpopulation

Evolvedpopulation

Phenotypes (fur color)

Stabilizing selection Directional selection Disruptive selection

Sexual Selection In intersexual competition (or mate

choice), individuals of one sex (usually females) are choosy in picking their mates, often selecting flashy, strong, resourceful or colorful mates

eg. In some bird species, the female chooses the male who can make the biggest pile of rocks. When the closest rocks are miles away, it takes a great effort to get them to the breeding site, and only healthy males can accomplish the task.


What is a species A species is a population of individuals that

share common traits and can mate to produce viable offspring that show recruitment.

A Chihuahua and a Great Dane are the same species. They can mate and have offspring that can have offspring.

A Horse and a Donkey are not the same species. They can mate and have viable offspring (known as, Mules), but all Mules are male and all Mules are sterile, so they do not exhibit recruitment.

Speciation Speciation is the creation of a new species through

Evolution and reproductive isolation

Reproductive isolation can be:

Geographic: Fish in Death Valley Ponds

Behavioral: Fire Fly Mating system

Anatomical: Fruit Fly Lock and Key mechanism

So if a population of a given species is reproductively isolated, they will respond to environmental pressures differently than the rest of the species and will change over time. Given long enough the two populations will become different species

Specialization There is a tendency for species to become

specialized/adapted to a specific resource.

Once the species becomes specialized so that it can ONLY use ONE resource it is “doomed to extinction”.

This is why the ultimate fate of all species is extinction.

California Condor

Everglades Kite

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Ground Rules for Behavioral Ecology What biological concepts and terms you need to remember and understand in order to make the field of Behavioral Ecology