Unit 4 Bio

evolution

change over time

• Changes to populations (not individuals)

• Changes to the genetic make-up

• Changes that can be passed to offspring

-is a theory

Lamarck

argued for inheritance of “acquired characteristics”,

• Changes in behavior → physical changes → changes in offspring

e.g., Wading birds

– Parents stretched their legs while moving through water. (had short legs before)

– Offspring had longer legs

Darwin

• Five-year voyage on HMS Beagle sailing around the world

-Finches all had diff. beak size correlated to food source in habitat

•Gathered a large body of evidence

• Theory of evolution based on Natural Selection

Variations, reproductive success varies, competition, adaptation

Four major principles of Natural Selection

Neo-Darwinism

• Ties together the modern concept of genetics and Darwin’s theory of Natural Selection

•Genetic variation (different alleles) exist in populations.

•Alleles that provide an advantage will be maintained in the population.

•Mutation, coupled with changes in the frequency of alleles, brings about evolution

fossils

• Preserved remnants of organisms

– Hard parts of organisms

• Bone

• Teeth

• Shells

– Imprints

• Leaves (within rock after mud hardened over top)

– Tracks

• Footprints

• Trails

branch points

Transitional fossils provide evidence of this in evolution (e.g., Basilasaurus shows that ancestors of whales had legs and was link between 4-legged ancestor and modern whale)

pharyngeal pouch and tail

Comparative embryology (comparing embryos) among vertebrates shows that they have these features in common

homologous structure

• Same basic, physical structure but may have different function

• Evidence of common ancestor

• Example: the forelimb of animals (whale, bird, bat, horse, etc. have similar bone structures but birds use theirs to fly while we use hands to grasp)

analogous structure

• Similar function but achieved by different physical components

•Did not have common ancestor

•Bird wing

–Support = bone

–Surface area = feathers

• Insect wing

–Support = veins

–Surface area = membrane

•Bat wing

–Support = bone

–Surface area = skin

artificial selection

the human-controlled breeding of organisms

• (If humans can bring about changes then changes can occur by natural selection)

similar

The more similar the amino acid sequence, the more _____ the DNA and more related the organisms are

fossils, anatomical structures, biogeographical and biochemical evidence, artificial selection

these provide evidence of evolution

Gene pool

The sum of all alleles in a population. Microevolution results from changes to this.

Allele frequency

–How often a particular allele appears in the population

–How many members of the population have dominant allele or the recessive allele

mutation, genetic drift, gene flow, artificial selection, natural selection

these bring about changes in a gene pool

mutation

• Introduction of new alleles.

•Relatively rare events compared to the others discussed

• Evolution most often results from changes in the frequency of alleles, not this

Genetic Drift

–Alterations in the gene pool in a random manner. (Not natural selection)

––Important to small populations. (change can be dramatic)

•e.g., Founder Effect and Bottleneck

Founder Effect

Example of Genetic Drift

-Small population becomes isolated from larger, original population and gene pool changes

-Small group moves to new location OR small group is isolated within original population

Hutterites and Amish

Examples of Founder Effect

Bottleneck

Example of Genetic Drift

•Random loss of a large portion of the original population.  Remaining individuals have less genetic variability.

-original population isn’t there anymore (like no more ppl that left Europe are still in Europe)

Endangered Species (Cheetahs and Northern Elephant seals)

Examples of Bottleneck

Gene Flow

• Movement of alleles between populations.

• Tends to reduce differences between populations but maintains genetic diversity

-e.g., brown beetles with green beetles. We’re not taking away the green allele but adding to it; changes the frequency of the alleles

artificial and natural selection

These are non-random changes

Artificial Selection

• Interbreeding to increase the frequency of desired traits.

• Often seen in agriculture, companion animals

• English bulldogs

• Toyger– Domestic cat bred to look like tiger

stabilizing, directional, diversifying

three outcomes of natural selection (______ selection)

survive and breed

adaptive value means better able to this and this

stabilizing selection

(outcome of natural selection)

• Phenotypes in the middle range are favored.

• Favors reproduction of well-adapted individuals near the average.

e.g., Human Birth Weight

directional selection

(outcome of natural selection)

• One phenotype is favored over another, resulting in a steady shift to one direction.

• e.g., Peppered moths – dark moth stands out against gray bark and could be prey, but grey moths can stay hidden so dark shifts to lighter color

disruptive selection

(outcome of natural selection) • Least common

• Both extremes of the phenotypic range are favored over middle.

• e.g., Grove snail

– Yellow bands

– Dark brown bands

– Not a color between

• or Black-bellied seed cracker

—Birds with either large or small beaks

species

– Common features such as anatomy and metabolism

– The ability to exchange genetic information

– Ability to interbreed and have fertile young

speciation

how species come about

• When populations of the same species become separated, they undergo Genetic Drift. 

– Geographically

– Anatomically

– Behaviorally

• These genetic changes could result the two populations no longer being able to interbreed and have fertile young, resulting in this

Linnean

– System of classification based primary on appearance and function

– Pre-Darwin

            -evolution doesn’t play a role in this

phylogeny

– Examines relatedness based on evolutionary perspective

– Relatedness based on common ancestor

            -more impt. than appearance b/c they can look diff. but have similar ancestor

– No system for naming

cladogram

tool used by phylogeneticists

• Clade = group with similar characteristics

            -shows evolution (e.g., lizard has no hair but then tiger does; loss of tail and then gorilla)

relatedness

organisms are classified based on this

– Anatomy and physiology

– Types of Metabolism

– Evolutionary progression related to other organisms

– Ability to interbreed and have fertile young

– Genetics

relatedness is determined by?

domain, kingdom, phylum, class, order, family, genus, species

levels of the linnean system of classification from most to least inclusive (Dashing King Philip Came Over For Grape Soda)

genus and species

binomial nomenclature is organized like this

Bacteria, Archaea, Eukarya

the three major categories of domains based on genetic material

archaea

(type of domain)

• Prokaryotes

• Unicellular

• Live in extreme environments

– Salt lakes (Halophiles)

– Hot springs (Thermophiles)

– Swamps and animal guts (mehanogens)

• Diversity in shape, structure, and metabolic activity

bacteria

(type of domain)

• Prokaryotes

• Unicellular

• Environments like humans

– E. coli in your intestines provides you with vitamins

• Similar in structure to each other

Eukarya

• All Eukaryotes

• Divided into 3 Kingdoms + Protista

– “Protista” – not a true kingdom but we’ll use it as a group to help organize those organisms (b/c they’re all so diverse)

– Fungi

– Plantae

– Animalia

Protista

• of the domain eukarya

• Very diverse group – especially in how they obtain nutrition

• Currently reclassifying into new kingdoms

• Most are Unicellular (Paramecium)

• Sexual and asexual reproduction; if sexual - no embryo

• Three major subgroups:

– Protozoans, Algae, Slime Molds

subgroup protozoans

• Major subgroup of protista

• Unicellular

• Most are heterotrophs – consume food to obtain carbon and energy (ingest)

• Giardia, amoeba, paramecium

subgroup slime molds

• Major subgroup of protista

• Heterotrophs

• “Absorb” nutrients

• Ingestion vs. Absorption

-absorption: release digestive enzymes into envir., nutrients are broken down, and nutrients are absorbed by the cell

subgroup algae

• Unicellular and multicellular

• Autotrophs – make their own food using energy from the sun and CO2

• Diatoms and brown algae

Fungi

• kingdom of the domain eukarya

• May or may not have cell wall, if there’s a cell wall it will be made of chitin

• Heterotrophs - absorption

• Unicellular and multicellular

• Sexual and asexual reproduction

• Nonmotile – can’t change locations

• Morels, yeast

plantae

•kingdom of the domain eukarya

• Cellulose cell wall

• Autotrophs - energy from sun

• Sexual reproduction

• All green plants

animalia

•kingdom of the domain eukarya

•Multicellular → tissues and organs

• Derived from a zygote which forms embryo

• Heterotrophs - ingestion

• Motile at some stage of life cycle

• Heterotrophs - ingestion

• Motile at some stage of life cycle

• Rotifers, insects, humans

Number of Germ Layers, Type of Symmetry, Body Plan, Segmentation, Type of Skeleton

classification criteria for animals

germ layers

these layers of cells form during embryonic development

• will form tissues

            e.g., skin, muscle, bone, nervous tissue

—diploblasic and triploblastic

diploblastic

–Two germ layers

–Less complex organism (jellyfish)

triploblastic

–Three germ layers

–More complex organisms (human)

gut, endoderm, ectoderm

diploblastic germ layers

gut, endoderm, mesoderm, ectoderm

triploblastic germ layers

asymmetry

(type of symmetry)
–No place at which you could bisect the organism into similar halves

radial

(type of symmetry)

– Central point around which you bisect the organism many times

– Sea stars, jellyfish

bilateral

(type of symmetry)

– One point at which you bisect the organism (down the middle)

– Humans

sac

(type of body plan)

– “Gastrovascular Cavity”

– There is one (same) opening by which food enters and waste exits

– Inefficient (greater chance for food to get lost before nutrients are taken in)

tube-within-tube

(type of body plan)

– “Complete Digestive System”

– Food enters one opening and digestion takes place within an internal tube

– Waste exits from other opening

– More efficient

segmentation

• Repetitive body parts – e.g., millipede, finger bones

• Not found in all animals

hydrostatic

(type of skeleton)

– Shape and support of body is provided by fluid within the animal

– Worms

exoskeleton

(type of skeleton)

– Shape, support, and protection is provided by tough material on the outside

– Crab shell

endoskeleton

(type of skeleton)

– Shape, support, and protection is provided by tough material on the inside

– Humans, fish bones

behavior

• Any action that can be observed and described.

• Virtually all living organisms demonstrate some form of this

tropism, circadian movements, rapid movements

plants demonstrate movements in these ways

tropism

plant growth moving toward or away from stimulus

phototropism

• Plant growth toward light

gravitropism

• Plant response to gravity

• Roots = positive (toward source of gravity) this

• Shoots = negative this

thigmotropism

• Plant response to touch

• Allows tendrils to curl around a support

• Response to touch

• Allows tendrils to curl around a support

circadian movements

• Behaviors on 24- hour cycles

• Leaf movements (up during day, down at night)

• Flower openings– Morning glory and moonflowers

rapid movements

• Leaves

– Leaves of a Venus flytrap snap shut to capture an insect– (Video)

• Seed or pollen dispersal

– Squirting cucumber– pops open as person walks by, putting seeds on them and causing them to disperse the seeds

environmental stimulus

this triggers plant behaviors/production of hormones which results in growth

genetic basis of behavior

fruit fry larvae (rovers vs. sitters; adapted for low vs. high density population), european pied flycatcher (prefer flycatchers song), and schooling in fish show this

taxis

• Animal changes location in response to a stimulus (like taxi that moves)

• An automatic response

– Positive response = moves toward stimulus

– Negative response = moves away from stimulus

chemo-this (e.g., bees release pheromones and other bees follow) and photo-this

taxis, reflex, fixed action patterns

types of innate behaviors

reflex

• Neurological response – requires a nervous system

• Nerve impulse travels to integrator (brain or spinal cord) and then message to effector (a

muscle)

• Knee jerk response

• Pulling your hand from a fire

fixed action pattern

• Stereotyped - performed in a similar manner by all members of the species

• Spontaneous

• Often coordinated movements

• Not learned

• Graylag Goose

 e.g.,

—Egg retrieval behavior – if egg rolls out of the nest it has to be retrieved

—Male sticklebacks defend their territory by attacking other males.  Attack is response to red

color not present on females.

—Mating dances as in the ostrich

imprinting

• Takes place during a critical time and is irreversible

•Critical period

–Varies with animal and behavior

–Geese must imprint on moving object within 2 days of hatching or will not imprint on

anything.

habituation

• The animal stops giving the response due to repetition or lack of reinforcement.

•No punishment if no response; no reward for response

•e.g., Crows learn that scarecrow won’t harm them; they get used to being around the scarecrow since there’s no punishment

cognition

Ability of the nervous system to perceive, store, process and utilize information from sensory input.

• Ability to integrate information before responding (plan ahead)

• Ravens and Crows

– Use tools to obtain food

– Ability to plan ahead; select tools for use in the future

• Primates

• Primates– Modify tools to make them more efficient.

behavior and other traits

the silver fox shows that there is a genetic link between this and this

plant behaviors

• Stimulus

– Environmental

• Response –

– Tropisms – Chemical (hormones)

– Rapid movements – Electrical

– Response is the same each time the stimulus is encountered

– Response can’t be modified

innate animal behaviors

• Stimulus – Environmental

• Response –

– Involves input from sensory organs

– Immediate response

– Response is the same each time stimulus is encountered

– Response cannot be modified

learned animal behaviors

• Stimulus

– Environmental

– Internal

• Response –

– Involves input from sensory organs

– Behavior can be modified

– Response can be delayed