Biology Exam 4
Homo erectus
"Upright man" these hominids became skillful hunters and invented more sophisticated tools for digging, scraping and cutting. They also became the first hominids to migrate from Africa. Also were the first to use fire.
Where did early hominin evolution take place?
-70% of the time hominins have been around, we lived and died in Africa. This is clear because the earliest hominin fossils have been found outside Africa (1.8 MYA) but found later fossils within the continent
two parts of allopatric isolation
1. geographic isolation--resulting in different characteristics in the organisms 2. the evolution of internal characteristics (intrinsic isolating mechanisms)
Mutation
Alteration in organism's DNA; generally has no effect or a harmful effect. But beneficial or "adaptive" mutations are indispensable to evolution -usually do not further survival -ex. this is how eyes and wings were created
how do all embryos start out?
As clusters of nearly identical cells Then they partition itself into specialized segments which develop into the final form of the animal
charles darwin
British naturalist who brought together the central theory of evolution; traveled for four years exploring for new evidence -most famous were the galapagos' finches
If the world's history were compressed into one hour, what kind of life appeared during...the first 50 minutes?
Microbes and single celled organisms
What are the characteristics of Homo neanderthalensis?
Migrated great distances, short (5'6") and stout, powerful, heavy "double arch" brow, receding chin, big-boned, large joints, brain capacity slightly larger than us
can a single individual cause evolution?
No, it is not the individual that involves but it's the population. Populations cause evolution through shuffling, addition, and deletion of genetic material...need generations to carry out these evolved traits.
Describe how whales swim:
Same as otter - unjulating its spine up and down Same as how land mammals use there spine when running
When was the first fossil record found of hominins?
The first fossil record of a homnini came in 1856 with a skull that was human and ape like (Neander)
bottleneck effect
a change in allele frequencies in a population due to chance following a sharp reduction in the population size -leads to low genetic diversity
microevolution
a change of allele frequencies in a population over a relatively short period of time. -micro because it's WITHIN a population at the smallest scale
polygenic
a character under the control of many different genes -ex. height -"continuously variable" but in a range (bell-curve)
sexual selection
a form of natural selection that produces differentials reproductive success based on differential success in obtaining mating partners -some "prettier" members of the population mate more than others -ex. peacocks
species
a group of organisms that can successfully interbreed with one another in nature but that don't interbreed successfully with members of other such groups
What's an example of polyploidy?
a hybrid offspring carried out usual practice of doubling its chromosome number in preparing for initial cell division. Cell fails to actually divide; supposed to put half its compliment of chromosome into once daughter cell and half into another. instead it DOUBLES the chromosomes but keeps it all in the same cell [this cell will then undergo regular cell division and has twice the usual number of chromosomes, meaning that every cell that follows will have doubled the amount of chromosome—now chromosomes can all pair up -reproductively isolated -this is sympatric speciation -oats, wheat cotton, potatoes -planters artificially induce polyploidy -conspiracy this sped up evolution with invertebrates turning into vertebrates
adaptation
a modification in the form, physical functioning, or behavior of organisms in a population over generations in response to environmental change.
polyploidy
a multiplication of the normal two sets of chromosomes to some other set number -plants can speciate in a single generation from polyploidy -speeds up evolution -all species number of chromosomes differ, but all come in pairs
natural selection of trees
a redwood tree will grow taller than others so that it may receive more sunlight; this offers an advantage for these trees so the trait is passed on.
paleoanthropologist
a scientist who studies fossils in the human lineage
Vestigal characters
a structure in an organism whose original function has been lost during the course of evolution -ex. auricular muscles (how humans wiggle ears)
radiometric dating
a technique for determining the age of objects by measuring the decay of radioactive elements they contain -this is how scientists are sure that the bedrock of the Earth ages back to 4.6 billion years ago.
If the world's history were compressed into one hour, what kind of life appeared during... .01 second?
all of human history, our civilization, our evolution
gene pool
all the alleles that exist in a population -a population or organisms can possess many allelic variants of each gene -think of the card deck example
If the world's history were compressed into one hour, what kind of life appeared during...the last 10 minutes
animal life
reproductive isolating mechanisms
any factor in nature prevents interbreeding between individuals of the same species or of closely related species -geographic isolation
phenotype
any observable trait that an organism has, physical and behavior
sympatric speciation
any speciation that does not involve geographic separation (all of the intrinsic isolating mechanisms can cause this) ex. the hawthorn and apple flies
What physical traits (adaptations) do all mammals have in common that relate to living on land?
breathe air, warm blooded, give birth to live organisms
interbreeding
breeding within close relatives
is the pace of speciation fast of long?
can take as few as a thousand years and as many as a several million to create new species.
Amish lethal microcephaly
cause exceedingly rare genetic conditions -results from infants with very small brains and life expectancy between 5-6 months. Happened in Pennsylvania when people of the same family dissent bred with one another -one defective allele would not cause trouble because the second allele provides sufficient information for the organism to function properly. but there will be serious defect if the child receives two defective alleles.
derived character
character unique to taxa descended from a common ancestor, like the tetrapod vertebrae.
Ancestral characteristics
characteristics that existed in an ancestor common to all of them. About 50,000 species of animals possess dorsal vertebral columns (backbone—some went on to animals that have four limbs, called tetrapods)
russel wallace
co-discoverer of evolution, made a living collecting bird and butterfly specimens from South America, believed natural selection shaped evolution, all his specimen burned on the boat ride home
homology
common structures in different species that result from a shared ancestry
How is it possible to have liger or tigons?
created in captivity; would never happen in nature even if their ranges overlap -would not be considered species by Mayr (believed species are of "natural" populations)
evolution
defined as any genetically based phenotypic change in a population of organisms over successive generations
mosaic pattern
different features developed at different points in time in different species.
what are the six intrinsic reproductive isolating mechanisms?
ecological, temporal, behavioral, mechanical, genetic isolation, and hybrid infertility/inviability
macroevolution
evolution that results in the formation of new species or other large groupings of living things
intrinsic isolating mechanisms
evolved in anatomy, physiology, or behavior that prevent interbreeding between individuals of the same/closely related species
Geospiza fortis
example of evolution in action: continues to adapt to changing environmental conditions -beak size increase by 5-6% more favorable for picking up seeds -simple some traits are favored over others
analogy
feature in different organisms that is the same in function and superficial appearance. - nothing to do with common descent; they merely show that the same kinds of environmental pressures lead to the same kinds of physical feature -ex. a lipotern and a horse having 4 legs
geographic isolation
form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water
Taung baby
found by Raymond Dart; Australopithecus Africanus ¨southern ape of Africa¨
theory
general set of principles supported by evidence that explains some aspect of the natural world
alleles
genes that come in variant forms-- one from father and one from the mother ex. eye color
genotype
genetic makeup of an organism
Stabilizing selection
intermediate forms of a given character are favored over extreme forms -ex. human birth weights--want average and healthy
What happened 220 million years ago?
mammals evolved from reptiles, but did not diversify in a steady way
population
members of a species that live in a defined geographic region at a given time -usually geographically isolated
Gene flow
movement of alleles from one population to another. occurs when individuals move between populations (migration) or when one population of a species joins another, assuming the second population has different allele frequencies than the first.
migration
movement of individuals from one population into the territory of another -ex. birds or plants
What are the five agents of microevolution?
mutation, gene flow, genetic drift, sexual selection, and natural selection
What's the driving force behind evolution?
natural selection
Are archaea species?
no, they do not interbreed because they multiply through simple cell division
what do a whale, cat, bat and gorilla all have in common?
one upper bone, two intermediate bones, mine to five digits -all come from a common ancestor
Lamarck's theory
organisms changed form over generations through the inheritance of acquired traits. -animals would acquire enough changes that one species would diverge into two, extending all the way to human beings. this is wrong !!!
Hardy Weinberg equation
p^2+2pq+q^2=1
Common descent with modification
particular groups, or species, of living things can undergo modification in successive generations, with such change sometimes resulting in the formation of new, separate species (branches off from single ancestor)
What do all organisms have during some point of their embryonic development?
pharyngeal slits; this means all organisms share a common vertebrate ancestor, which had the slits
Difference between species and populations
populations are reproductively isolated and stay confined within their species
Hardy Weinberg Principle
principle that allele frequencies in a population will remain constant unless one or more factors cause the frequencies to change -equilibrium
what are the 8 categories of taxon?
species, genus, family, order, class, phylum, kingdom, and domain
what are the three polygenic modes of natural selection?
stabilizing, directional, disruptive
Morphology
study of the physical forms that organisms take.
Homini
taxon of human-like beings
modern synthesis
the convergence of several lines of biological research into a unified evolutionary theory
Speciation
the development of new species through evolution -flow of genes between populations
what does q stand for?
the less common r allele
cytochrome c oxidase tells us...
the longer it has been since any two species shared a common ancestor the buffer the differences in the number of their cytochrome c oxidase. -ex. pigs vs. humans =13 but humans vs. yeast=66
what does p stand for?
the more common R allele
taxon
the organisms in any of the eight categories in the taxonomic system that make up a group of living things
natural selection
the process through which traits that confer a reproductive advantage to an individual organism grows more common in populations of organisms over successive generations
adaptive radiation
the rapid evolution of many species from a single species that has been introduced to a new environment -perceived most readily on islands and small geographic locations -to take place a given environment must provide a species with a set of unfilled niches
homologous
the same structure owing to inheritance from a common ancestor
Fitness
the success of an organism in passing on its genes to offspring relative to other members of its population at a given time. -allele frequencies increase in a population only if it has MORE offspring than other members of its generation
Name some characteristics of Lucy
transition from ape-like to human-like. she was bipedal, possessed long arms, short legs, and feet built for grasping—no longer exclusively lived in trees, but may have spent time in them, smaller cranium Gave rise to our own genus (homo)
Ecological isolation
two closely related species of animals may overlap in their ranges and yet feed, mate, and grow in separate areas called habitats. This means that the species rarely meet up/ come in contact w one another -ex. Lions and tigers could interbreed, but don't)
Lactose frequencies
-An example of convergent evolution; the human ability to digest milk is not natural at first. evolved 3 separate times over 7000 years—East Africa, Northern Europe, Middle East -origination by means of a mutation that occurred within a population of humans who had began to domesticate milk-yielding animals -allowed individuals to keep producing an enzyme called lactase once past infancy, a change that gave these individuals a lifelong ability to digest lactose in milk (spread through the local populations then larger so now a substantial minority of human adults can digest milk)
All land mammals are classified as tetrapods What does this mean?
-Have four limbs -All descended from ancestor that had limbs : -Left the water 375 million years ago -Got reptiles and mammals from it
A scientist, Dr. Bateman, was studying the similar segmentation patterns of animals. What mutations did he observe that related to these segmentation patterns?
-Said that skeletons revealed an underlying structure of repeating segments -Said some animals developed with segments in the wrong places -Random changes were the fuel to evolution -Mutations that he saw -Crab claws -Antlers
What are the two most defining characteristics of a hominid?
-The two most important defining characteristics of a hominin are tooth structure and upright or "bipedal" walking.
How do the bones of the early tetrapod fish, such as Acanthostega, resemble ours?
-They developed fingers first and then left the water -Found a hand (paddle) -Fish with fingers -Proved that some fish had arms and legs in the water
How was Toumai clearly a hominin and not an ape?
-because of the canine teeth (smaller and less sharp than apes) -enamel on teeth is thicker -slope of face; lower jaw does not jut out beyond the eyes like apes'
Hormo ergatser
1.6 MYA, little boy "Turkana Boy" found in Kenya, grown to maturity, height of 6 ft. brain more than half the size of homosapiens, modern face, longer limbs
Why do chimps have 48 chromosomes and we have 46?
2 chromosomes were separate in primates became fused to form one single chromosome -able to tell in the chromosome had 2 centromeres, and it did when tested and it's on chromosome 2 in humans
When did mammals first appear?
200 million years ago
How long ago and where did Australopithecus africanus (Lucy) live?
3.18 million years ago in Ethiopia;
when did LIFE appear on Earth?
3.5 billion years ago
How old is the Earth?
4.6 billion years old
Whale Valley is an archeological site located in the Sahara Desert. How could there be whale skulls here?
40 million years ago the desert used to be the southern Mediterranean sea
Cambrian Explosion
A burst of evolutionary origins when most of the major body plans of animals appeared in a relatively brief time in geologic history; recorded in the fossil record about 545 to 525 million years ago. -Greatest fossil find in history: found 1000 different sea dweller fossils that were caught in a mudslide -Shows us all the different body plans -Evolution messes with the genes
homo sapien
A species of the creatures Hominid who have larger brains and to which humans belong, dependent of language and usage of tools.
What are trilobites? Who are their descendants?
A trilobite is a prehistoric fish w/ an exoskeleton its descendants are crabs (horseshoe crab was the example in class), lobsters, insects, and spiders
Genetic drift
Chance alteration of gene frequencies in a population. Most strongly affects small populations. Can occur when populations are reduced to small numbers (bottleneck effect) or when few individuals migrate to a new location and start a new population (founder effect) - can only be replaced by a mutation or migration
hybrid inviability/infertility
Even if fertilization occurs successfully, the offspring may not survive, or if it survives, may not reproduce. -ex. Mules which are a mix of horse and donkey are infertile
gametic isolation
Even if physically compatible, and mating occurs, an embryo will not form if the egg and sperm don't fuse properly (not compatible with one another)
mechanical isolation
Even if they attract one another, they cannot mate if they are not physically compatible (different sized sex organs—like the alpine butterflies)
behavioral isolation
Even when populations are in contact and breed at the same time, they must choose to mater with one another; often based off "courtship" and mating displays. -ex. Birds hear proper songs, spiders do proper dance, etc.
Curvier's theory
Found layer upon layer of complex forms (fossils) and believed a series of catastrophes had wiped these animals out. -thought create then would make completely different beings in more complex forms (wrong!!)
Which hominin was the first to leave Africa? Why did they leave?
Homo erectus was the first hominin to leave Africa—traveled all the way to China because it could. -Now had the ability to take longer strides with longer legs and foot structure that allowed each step to end with a propulsive push off the toes (the kind of stride we have today)
What type of animal did the Creodont skull that Dr. Gingrich discovered resemble?
In Palestine found the back of a skull -Similar to a wolf, but different -Distinctive inner ear that today is only found in whales -Whales had evolved from land animals (had once been 4 legged animals with a pelvis)
Where are hybrids most likely to be found?
In plants (seed germination, pollination)
problems with interbreeding?
Inbreeding can lead to serious genetic defect ranging from improper joint formation to heart defect to deafness (in the cocker spaniel example, happened to one-fourth of them) -brings together rare, identical alleles—recessive alleles required for many genetic disease. random breeding brings these alleles apart and provides genetic diversity.
How do species arise?
two populations of a single species (say a species of birds fly to a different location) continue to breed with one another, with individuals moving between locations, each population will SHARE in whatever allele frequency changes are going on with the other population -evolve together -through changes (natural selection, genetic drift, etc) the two populations change in the form and behavior; when geographically united, they are two species....speciation has occurred.
biological species concept
uses breeding among organisms to make classifications -only applies to sexually reproductive organisms
founder effect
when a small subpopulation migrates to a new area to start a new population, likely to only bring with it only a portion of the original population's gene pool -interbreeding (less diversity; mutations)
allopatric speciation
when geographical barriers divide a population and the resulting populations then go one to become separate species
Directional selection
when natural selection moves a character toward ONE of its extremes -ex. evolution towards a larger brain size
disruptive selection
when natural selection moves a character towards BOTH of its extremes which appears to occur the least in nature out of the three modes
convergent evolution
when nature has shaped two separate evolutionary lines in analogous ways -takes place within a species
temporal isolation
when two populations share the same habitat/ even come in contact, they cannot mate with one another if they breed at different times -ex. Flowers releasing pollen at different times; gene flow cut between them