Biology Chapters 13-16

Charles Darwin

(1809-1882) English naturalist. He studied the plants and animals of South America and the Pacific islands, and in his book On the Origin of Species by Means of Natural Selection (1859) set forth his theory of evolution. *Fossils started before his time mid 1700s Supported Ideas: -Species change over time and living species risen from earlier life forms -Strongly influenced by Principles of Geology by Scottish geoglogist Charles Lyell --> helped darwin realize that natural force gradually change earth;s surface over time and these forces still operate in modern time. (believes slow growth of mountains accounted for fossils of marine organisms being found there) -In the mid 1850s Alfred Wallace, a British naturalist conceived a theory identical to Darwin's. -postulated that as the desendants of the eariest organism spread into various habitats over millions of year, they accumulated diverse modifications/adaptions, that accomodated them to diverst ways of life. (history resembles a tree) -basic but monumental ideas

Oparin's Hypothesis

(1920s Russian biochemist A. I. Oparin) -proposed that the primitive atmosphere contained the gasses methane, ammonia, hydrogen, and water, and that chemical reactions in that primitive atmosphere produced the first organic molecules. (him and British geneticist J. B. S. Haldane) -proposed that the conditions on the early Earth could have generated a collection of organic molecules that in turn could have given rise to the first living organisms.

1st organic molecule

-Small organic molecules must have first appeared, most likely occurred when inorganic chemicals were energized by lighting or UV radiation. -First, simple organic molecules containing nutrients formed *stage proceeding this would be the formation of polymers, then after that the origin of a mechanism of polymer replication; primitive form of heredity, finally at some point the polymers must have formed aggregate having chemical characteristics different from their surroundings.

How are fossils formed

-Some animals were quickly buried after their death (by sinking in mud, being buried in a sand storm, etc.). -Over time, more and more sediment covered the remains. The parts of the animals that didn't rot (usually the harder parts likes bones and teeth) were encased in the newly-formed sediment. -In the right circumstances (no scavengers, quick burial, not much weathering), parts of the animal turned into fossils over time. -After a long time, the chemicals in the buried animals' bodies underwent a series of changes. As the bone slowly decayed, water infused with minerals seeped into the bone and replaced the chemicals in the bone with rock-like minerals. The process of fossilization involves the dissolving and replacement of the original minerals in the object with other minerals (and/or permineralization, the filling up of spaces in fossils with minerals, and/or recrystallization in which a mineral crystal changes its form). -This process results in a heavy, rock-like copy of the original object - a fossil. The fossil has the same shape as the original object, but is chemically more like a rock. Some of the original hydroxy-apatite (a major bone consitiuent) remains, although it is saturated with silica (rock).

Miller-Urey Experiment

-Suggests that earth allowed the spontaneous creation of organic compounds because the atmosphere did not have O2, O2 is corrosive: as oxidizing agent it breaks chemical bonds by extracting electrons. -Before prokaryotes added O2 into the air, earth probably had a reducing environment instead of oxidizing one--> tends to add electrons to molecules. (could cause simple molecules to combine to form complex ones) -Construction of these molecules requires energy, which was abundant on earth (miller and urey reasoned) lighting, ultra violet radiation with greater intensity *ozone layer not present -constructed an apparatus to test if organic molecules would form from inorganic ones under conditions of early earth -Apparatus: A flask of warm water to represent primeval sea, The atmosphere consisted of H2, CH4, and NH3- gases scientist of 1950s believed were present, Electrodes discharged sparks into the gas mixture to mimic lightning, Below the spark chamber was a glass jacket called a condenser that surrounded the apparatus, filled with cold water the condenser cooled and condensed the water vaporin the gas mixture causing "rain" along with dissolved compounds to fall back into miniature sea, Flask solution began to change color as material circulated through the apparatus -They got mainly organic compounds of biological quantities, amino acids were formed abundantly. -Made most of 20 amino acids found in organisms,sugars,lipids,nitrogenous bases in DNA and RNA. *Now know that modern volcanoes emit CO1,CO2,N2,Water vapor. H2,CH4,NH3 not major components, could have been traces of Oxygen -Initial chemical resources may have been produced in underwater hydro-thermal vents/volcanoes, some of polymerization reactions that made larger organic molecules could have occurred in different areas (beaches they dried out and heated up)

Sources of Variation among a population

1. Mutation. This is some error in the replication of DNA during cell division. This is a *huge* category as there are many kinds of mutations. The most important (from the point of view of evolution) is gene duplication (also called 'gene amplification'). But there are also point mutations, substitutions, deletions, insertions, frameshift errors, translocations, transpositions, inversions, etc. 2. Sexual combination. This refers to the fact that any mating between two individuals produces an offspring with a genome different from *either* of its parents. This is a *huge* source of variation within a population, as it produces many different *combinations* of traits, each of which can have its own advantages and disadvantages. Thus sexual reproduction can produce far more variation than asexual reproduction, where all variation is dependent on mutations. 3. Recombination and crossing over. This refers to processes during various stages of DNA replication where DNA is broken and then joined to other chromosomes. The most common form of this is crossing-over during meiosis where DNA is exchanged between homologous chromosomes, but there are other processes, such as end-joining between non-homologous chromosomes that can occur.

Evidence of Evolution

1. the fossil record of change in earlier species 2. the chemical and anatomical similarities of related life forms 3. the geographic distribution of related species 4. the recorded genetic changes in living organisms over many generations

Reproductive barrier

A biological feature of species that prevents it from interbreeding with other species even when populations of the two species live together

Polyploid cell

A cell with more than two complete sets of chromosomes

Microevlution

A change in a populations gene pool over a succesion of generations ,evolutinoary changes in species over relatively breif periods of geological time

Genetic Drift

A change in the gene pool of a population due to chance

Mutation

A change in the nucleotide sequence of Dna; ultimate source of genetic diversity

Species

A group whose memebers poses similar anatomical characteristics and have he ability to interbreed

radiometric dating

A method for deteminging the age of fossils and rocks from the ratio of a radioactive isotope to the nonradioactive isotope(s) of the same element in the sample

Paleontologist

A scientist who studies fossils: -the structure of organisms -what they ate -what ate them -the environment in which they lived -to classify organisms from oldest to most recent

Geologic time scale

A time scale established by geologists that reflects a consistent sequence of historical periods, grouped into four eras: Precambrian, Paleozic, Mesozoic, and Cenozoic

Hybrid inviability

A type of postzygotic barrier between species; the species remain isolated because the hybrid zygotes fail to develop or to reach sexual maturity

Hybrid sterility

A type of postzygotic barrier between species; the species remain isolated because the hybrids fail to produce functional gamete

Hybrid breakdown:

A type of postzygotic barrier between species; the species remain isolated because the offspring of hybrids are weak or infertile.

Behavioral isolation

A type of prezygotic barrier between species, two species remain isolated because individuals of neither species are sexually attracted to individuals of the other species.

Gametic Isolation

A type of prezygotic barrier between species; the species remain isolated because male and female gametes of the different species cannot fuse, or they die before they unite.

Mechanical Isolation

A type of prezygotic barrier between species; the species remain isolated because structural difference between them prevent fertilization

Habitation Isolation

A type of prezygotic barrier between species; the species remain isolated because they breed in different habitats.

Temporal Isolation

A types of prezyotic barrier between species; the species remain isolated because they breed at different times

Which came first Autotrophs of heterotrophs?

All organisms need a carbon source to survive. The pure definition of an autotroph is an organism that can use CO2 as its sole carbon source. This can be accomplished through photosynthesis (either producing oxygen or not) and quite possibly through other pathways. A Heterotroph is another name for a chemoogranotroph. Meaning an organism that gets energy by breaking down organic molecules (like sugars, or a large variety of other things). It is generally accepted that biomolecules can form spontaneously from the variety of gases that made up Earth's primitive atmosphere when UV energy is present. This has been reproduced in the laboratory. It is also true that many natural surfaces (such as certain types of clay) have catalytic functions for assembly of biomolecules. So, on early Earth there was accumulation of biomolecules, and with the help of catalytic substances self replicating molecules began to form. From there the leap was somehow made to self replicating organisms with genes and therefor directed assembly and replication of the organism itself, and directed metabolism. It is likely the chemoogranotrophs where the first replicating organisms because of the abundance of organic molecules present on the then sterile earth. It is also thought that there were early RNA "lifeforms" that were esentially self replicating RNA molecules that performed catalytic functions with themselves and with the environment. These "lifeforms" would obtain all of their building blocks from the surrounding environment, and all of the building blocks were spontaneously made from the Earth's primitive atmosphere and the Sun's energy, or radiation, or thermal energy, but the organism itself didn't use the carbon dioxide. So I guess heterotrophs (chemoorganotrophs) came first. There was no nead for autotrophs because the primary production was spontaneous due to the composition of the early atmosphere.

Variation

An organism that has characteristics resulting from chromosomal alteration

Anaerobe vs. Aerobes

Anaerobe: microorganism having the ability to live without oxygen, Aerobes: Microorganism that requires oxygen to survive.

Molecular Evidence

Cellular: -All organisms are made of cells, which consist of membranes filled with water containing genetic material, proteins, lipids, carbohydrates, salts and other substances. -The cells of most living things use sugar for fuel while producing proteins as building blocks and messengers. -Have many of the same organelles Molecular: -Different species share genetic homologies as well as anatomical ones. Roundworms, for example, share 25% of their genes with humans. -Similarites reveal their common ancestry. -In fact, the DNA code itself is a homology that links all life on Earth to a common ancestor. -DNA and RNA possess a simple four-base code that provides the recipe for all living things. In some cases, if we were to transfer genetic material from the cell of one living thing to the cell of another, the recipient would follow the new instructions as if they were its own.

Cytochrome C

Cytochrome c provides evidence of evolution because it is molecular biology. The variance of cytochrome c of different organisms is measured in the number of differing amino acids. Each of them differs as a result of a base pair substitution known as mutation.

Decent with modification

Darwn's intial phrase for the general process of evolution

Cladogram

Diagram showing how organisms are related based on derived characteristics such as feather, hair, or scales.

Phylogenetic trees

Diagrams that trace evolutionary history

Natural Seletcion

Differintail sucess in reproduction by different phenotypes resulting from interaction with the environment. Evolution occurs when natural selection produces changes in realtive frequencies of allels in a popilation gene pool.

Types of Evolution

Divergent Evolution: the accumulation of differences between groups which can lead to the formation of new species, usually a result of diffusion of the same species to different and isolated environments which blocks the gene flow among the distinct populations allowing differentiated fixation of characteristics through genetic drift and natural selection. Example: An example of divergent species is the apple maggot fly. The apple maggot fly once infested the fruit of a native Australian hawthorn. In the 1860s some maggot flies began to infest apples. They multiplied rapidly because they were able to make use of an abundant food supply. Now there are two distinct species, one that reproduces when the apples are ripe, and another that continues to infest the native hawthorn. Furthermore, they have not only evolved different reproductive timing, but also now have distinctive physical characteristics. Convergent Evolution: the process whereby organisms not closely related, independently evolve similar traits as a result of having to adapt to similar environments or ecological niches. Example: The North American kangaroo rat, Australian hopping mouse, and North African and Asian jerboa have developed convergent adaptations for hot desert environments; these include a small rounded body shape with very large hind legs and long thin tails, a characteristic bipedal hop, and nocturnal, burrowing and seed-eating behaviours. These rodent groups fill similar niches in their respective ecosystems. Co-evolution: The arms race. Cases where two (or more) species reciprocally affect each other's evolution. Coevolution is likely to happen when different species have close ecological interactions with one another. These ecological relationships include: Predator/prey and parasite/host, Competitive species, Mutualistic species Example: Plants and insects represent a classic case of coevolution—one that is often, but not always, mutualistic. Many plants and their pollinators are so reliant on one another and their relationships are so exclusive that biologists have good reason to think that the "match" between the two is the result of a coevolutionary process. One example of coevolution is bumblebees and flowers. the bumblebees move the pollen around, causing more flowers to grow.

Outcomes of Natural Selection

Diversifying selection example: Occurs when environmental conditions are varied in a way that favors individuals at BOTH extremes of a phenotypic range. Mice of very light and very dark have increased their numbers relative to intermediate(middle range) variants--> could have happened if their habitat background was very light and studded with dark rocks. Directional selection example: Shifts overall makeup of organisms by actin against individuals at one of the phenotypic extremes. A population of Mice may trend toward the darker fur color to blend into a shaded environment (of trees). Directional selection is most common during period of environmental change or when members of species migrate to some new habitat with different environmental conditions. Stabilizing selection example: Favors intermediate variants. Typically occurs in relatively stable environments, where conditions tend to reduce phenotypic variation. It has eliminated extremely light or extremely dark mice and the population has a greater amount of intermediate phenotypes (best suited to a stable environment). Prevails most of the time in most populations.

Source of energy

Energy came from the sun. lighting, and earth's heat. It triggered chemical reactions to produce small organic molecules from substance present in the atmosphere.

Haedy Weinberg Equation

Equation: p^2 + 2pq + q^2 =1 Conditions to be met: 1.Populations is very large 2.The population is isolated; that is, there is no migration of individuals or gametes into or out of the population 3.Mutation (changes in genes) do not alter the gene pool 4.Mating is random 5.All individual are equal in reproductive success; that is natural selection DOES NOT occur How to figure out P? P= 1 - Q How to figure out Q? Q= 1 - P Example: Using ww, Ww, WW 52/1000 are homozygous recessive p^2 + 2pq + q^2 =1 To find q: q^2= frequency of ww, 52/1000 = 0.052 q= the square root of the frequency (0.052) --> √0.052 q=0.2529 (aprox.) To find p: P= 1 - 0.2529 P= 0.7471 P^2= frequency of WW, (0.7471)^2 P^2= 0.55815841 To find 2pq: 2pq= frequency of Ww 2pq= 2(0.7471)(0.052)

Macroevolution

Evolutionary change on large scale; encompassing the origin of new taxonomic groups, evolutionary trends, adaptive radiation, and mass extinction

Gene Flow Examples

Examples: -The gain or loss of allels from a population by the movement of individuals or gametes into or out of the population -By Migration: Gene flow occurs when a member of one population is able to move to another population and reproduce, introducing its genes into the second population and increasing its genetic diversity. An example could be a fish being able to cross into another lake during a flood which is normally inaccessible. -By Emirgration This gene flow occurs when there is migration. The loss or addition of people can easily change gene pool frequencies even if there are no other evolutionary mechanisms operating. For instance, if all red haired people were to leave Scotland, the next generation there would likely have very few people with this trait.

Genetic drift Examples

Examples: Genetic drift is a change in the gene pool of a small population solely due to chance. -Population has to be infinitely large to rule out genetic drift -Natural selection is NOT evolved -Genetic drift is most influencial on populations 100 individuals or less *Two situations that can shrink populations down to a small size are bottle neck effect and the founder effect. Examples of bottle necking: -Genetic drift resulting from an event that drastically reduces population size; events such as *earthquakes, floods, or fires* may kill large number of individuals un-selectively -producing a small surviving population (unlike to have the same genetic makeup as the original population). -Certain alleles may present at higher frequency in the surviving population than in the original population, other may be present at lower frequency or not at all. Examples of founder effect: -Genetic drift in a small colony -The colonization of a new location by a small number of individuals. The smaller the sample size, the less the genetic makeup of the colonists will represent the gene pool of the larger population they left. -Explains relatively high frequency of certain inherited disorders amoung some human populations establish by small numbers of colonists. The allele frequency for certain traits may be MUCH high than the original population from which the founders came.

Evolution

Genetic change in a population or species over generation; all the changes that transform life on Earth, the heritable changes that have produced Earth's diversity of organisms.

Bottleneck effect

Genetic drift resulting from a drastic reduction in population size

Early atmosphere

Most likely contained H2O, CO2, CO1, N2, little CH4.

Directional selection

Natural selection that acts agains the relatively rare indivisuals of one end of the phenotype range.

Stabilizing Selection

Natural selection that favors intermediate variants by acting against extremes phenotypes.

Diversifying (disruptive) Selection

Natural selection that favors the extremes over the intermediate phenotypes.

Reproductive Barriers between species examples

Prezygotic Barriers: Temporal Isolation: P.radiata and P.muricata Monterey pine releases pollen in Feb. while the Bishop's pine does in April. ************************************************* Habitat Isolation: Two species of parasites living in different hosts will not have a chance to interbreed. ************************************************* Behavioral Isolation: Courtship ritual in blue-footed boobies as a behavioral barrier between species. ************************************************* Mechanical Isolation: Male copulatory organs of many insect species have a unique and complex structure that fits the female parts of only on species. ************************************************* Gametic Isolation: Male and female sea urchins of many different species release gametes but fertilization occurs only if species-specific molecules attach to each other. _______________________________________________________ Postzygotic Barriers: Hybrid inviability: frogs of the genus Rana Hybrids are produced occasionally but they do not complete development or frail. ************************************************* Hybrid sterility: A mule, offspring btwn female horse and male donkey. A mule never interbreeds with a horse or donkey. Gene pools of the horse and donkey remain isolated. ************************************************* Hybrid breakdown: First-generation of hybrids are fertile but the offspring of the hybrids are feeble or sterile. Many different cotton plants produce hybrids but the offspring of the hybrids do not survive.

Founder effect

Random change in the gene pool that occurs in a small colony of a population

Mutations Examples

Random errors in gene replication that lead to a change in the sequence of nucleotides; the source of all genetic diversity, heritable changes in genetic information. Example

Artifical Selection

Selective breedoing odf domesticated plants and animals to produce the occurence of desirable inheritted tairs in offspring.

Sexual vs. Asexual Reproduction

Sexual reproduction: Reproduction involving the union or fusion of a male and a female gamete resulting in a zygote that is genetically different from either parent. -Cross over -Random fertilization -Combination of gametes -Independent assortment Evolution will take place at a faster rate within sexual reproduction, it has an advantage in evolution because it can create genetically unique individuals which may yield organisms which are better adapted to a specific environment (greater chance of survival), and thus a species can evolve. Asexual reproduction: Reproduction that does not involve the union of gametes and in which a single parent produces offspring that are genetically identical to the parent Evolution will take place at a slower rate, evolution only occurring mostly due to mutations.

Single celled to multicellular organisms

Single-cell organisms, such as bacteria and protozoa, have been so successful in adapting to a variety of different environments that they comprise more than half of the total biomass on earth. Unlike animals, many of these unicellular organisms can synthesize all of the substances they need from a few simple nutrients, and some of them divide more than once every hour. What, then, was the selective advantage that led to the evolution of multicellular organisms? Organized patterns of cell differentiation occur even in some procaryotes. For example, many kinds of cyanobacteria remain together after cell division, forming filamentous chains that can be as much as a meter in length. At regular intervals along the filament, individual cells take on a distinctive character and become able to incorporate atmospheric nitrogen into organic molecules. These few specialized cells perform nitrogen fixation for their neighbors and share the products with them. But eucaryotic cells appear to be very much better at this sort of organized division of labor; they, and not procaryotes, are the living units from which all the more complex multicellular organisms are constructed.

Homologous structures Examples

Structures in different species that are similar because of common ancestry. Examples: The flipper of a whale, the wing of a bat, and the leg of a cat are all very similar to the human arm. All of the mentioned species have a large upper arm bone (the humerus on the human) and the lower part of the limb is made up of two bones - a larger bone on one side (the radius in humans) and a smaller bone on the other side (the ulna in humans). All of the species also have a collection of smaller bones in the "wrist" area (these are called carpal bones in humans) that lead into the long "fingers" or phalanges. Significance: -Similarities are evidence that life on Earth has a common ancient ancestor that the diverse species have evolved from over time. -The common ancestry of the species can be seen in the structure and development of these homologous structures, even if their function is different. -homologous structures became more and more important in deciding the final placement on the phylogenetic tree of life. Whales were once classified as a fish since they live in the water and have flippers. However, after it was discovered that those flippers actually contained homologous structures to human legs and arms, they were moved to a part of the tree more closely related to humans. In fact, it seems whales are much more closely related to hippos than fish.

Anatomical Structures

Structures that perform the same or similar function by a similar mechanism but evolved separately; different anatomy similar function. -common ancestry -different functions, similar structures *aka homologous structures

Taxonomy

The branch of biology concerned with identifying, naming, and classifying species.

Fossil record

The chronicle of evoltioin over million of year of geological time engraved in the order in which fossils appear in rockstrata. -provides evidence about the history of life on earth -shows how different groups of organisms have changed over time

adaptive radiation

The emergence of numerous species from a common ancestor introduced to new and diverse environments

Speciation

The evolution of a new species

Allopatric speciation

The formation of a new species as a result of an ancestral population's becoming isolated by a geographical barrier

Sympatric speciation

The formation of a new species as a result of genetic change that produces a reproductive barrier between the changed populaton and the parent population.

Gene flow

The gain or loss of alllels from a population by the movement of indivisuals or gametes into or out of the population

Biogeography

The geographical distrution of species

punctuated equilibrium

The idea that speciation occurs in spurts followed by long periods of little change

Overpopulation

The number of a people in an area exceeds the capacity of the environment to support life at a decent standard of living.

Order of Biological Evolution

The organization of living things can be seen like a pyramid or tree with 8 major levels or categories:Domain Kingdom, Phylum, Class, Order, Family, Genus, Species. There is a simple pneumonic that can help students remember the organization of nature: Kangaroos Play Cellos, Orangutans Fiddle, Gorillas Sing. If we take a Ring-tailed Lemur, we can trace it through the hierarchy of nature, taxonomy as follows, it belongs to: The Animal ...Kingdom sharing with all other members of this group the need to feed on organic matter (unlike plants which can create energy using light and minerals) The Chordate (or vertebrate) ... Phylum sharing with all other members of this group of animals, a back bone with a hollow nerve chord The Mammal ... Class sharing with all other members of this group of vertebrates, the ability to feed their offspring on milk and having a body covering which includes fur The Primate ... Order Sharing with all other members of this group of mammals, a thumb that can be opposed to the other digits, binocular vision and various more broadly defined characteristics (including high intelligence, relatively long maturation period for the young, dental similarities, tendency for complex social organization, and generally bearing one or two young) The Lemuridae ... Family Sharing with other members of this group of primates, a slightly longer nose, smaller brain, long slender limbs, a tail, more specific dental features including the grooming comb formed by the lower incisor and canine teeth The Lemur ... Genus Sharing with other members of this group of lemurs, scent marking methods, vocalizations, aspects of social structure and overall body shape The Ring-tailed Lemur ... Species A species is the primary unit of biological classification or taxonomy. Species members share a basic genetic similarity and can interbreed and produce viable or fertile offspring. It is important to be aware, when exploring the field of taxonomy, that as is true in many branches of science, it is always changing and evolving. As our knowledge deepens and our tools for investigation become more precise there are often shifts and changes in how we describe an animal from a taxonomic point of view. A classic case can be seen with Pandas. When first described by European scientists they were classified as bears or ursids... a family of carnivores (order) in the mammal class of vertebrate animals. Then for a few decades, scientists thought that they weren't bears and placed them, still within the carnivore order... but in a family closer to raccoons. In the last fifteen years, after further study and aided by the new science of gene mapping, pandas have been returned to the bear family... an unusual case of an older view being (at least for now) correct after all.

Hardy-Weinberg equlibrim

The principle that the shifting of genes that occurs during sexual reproduction, by itself, cannot change the overall genetic makeup of a population.

Homologous structure

The stuctures that are similar in different species of common ancestry

Comparative Anatomy

The study of body struction in different organisms

Population Genetics

The study of genetic changes in populations; the sicence of microevoltionary changes in population

Comparative Embryology

The study of the formation, early growth, and development of different oragnisms.

Molcular Biology

The study of the molecular basis of genes and gene expression; molecular genetics

Endosymbiont Theory

The theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by an ancestral eukaryotic cell. The engulfed cell and its host cell then evolved into a single organism

Gradualist Model

The view that evolution occurs as a result of population becoming isolated from common ancestral stock and gradually becoming genetically unqiue as they are adapted by natural selections yo their local environments; Darwin's view of the origin of species.

Reason for experiment

To examine what kind of environment would be needed to allow life to begin, tested for the occurrence of chemical origins of life. *First to show that amino acids and other organic molecules could have been generated on lifeless earth.

Molecular Clocks

Use DNA to estimate the length of time two species have been evolving independently

Dichotomous key

Used to identify organisms, characteristics given in pairs, read both characteristics and either go on to another set of characteristics OR identify the organism.

Lamarkian Theory of Evolution vs Darwinian Theory

What they Agreed on: Darwin and Lamarck both thought that life had changed gradually over time and was still changing, that living things change to be better suited and adapted to their environments, and that all organisms are related. Darwin and Lamarck also agreed that life evolved from fewer, simpler organisms to many, more complex organisms. *** Lamarck: Lamarck is best known for his Theory of Inheritance of Acquired Characteristics, first presented in 1801. If an organism changes during life in order to adapt to its environment, those changes are passed on to its offspring. He said that change is made by what the organisms want or need. For example, Lamarck believed that elephants all used to have short trunks. When there was no food or water that they could reach with their short trunks, they stretched their trunks to reach the water and branches, and their offspring inherited long trunks. Lamarck also said that body parts that are not being used, such as the human appendix and little toes are gradually disappearing. Eventually, people will be born without these parts. *Theory of Inheritance of Acquired Characteristics is DISPROVED* Why? If someone exercises every day, runs marathons, eats well, and is generally very healthy, the fitness is not passed on and the person's children still have to work just as hard to get that fit and healthy ****. Darwin: Darwin believed that the desires of animals have nothing to do with how they evolve, and that changes in an organism during its life do not affect the evolution of the species. He said that organisms, even of the same species, are all different and that those which happen to have variations that help them to survive in their environments survive and have more offspring. The offspring are born with their parents' helpful traits, and as they reproduce, individuals with that trait make up more of the population. Other individuals, that are not so well adapted, die off. Most elephants used to have short trunks, but some had longer trunks. When there was no food or water that they could reach with their short trunks, the ones with short trunks died off, and the ones with long trunks survived and reproduced. Eventually, all of the elephants had long trunks. Darwin's theory has been supported by a lot of evidence.

Modern Sythesis

a comprehensive theory of evoltion that incorporates geneticsd and include most of Darwin's ideas, focusing on populations as the fundamental units of evolution.

Population

a group of interacting individuals of a species permenent area or volume.

Aggregates

a mass or grouping of distinct individuals who are considered as a whole and are loosely associated with each other, broader term then population

Fossil

a preserverd remant of impression of an organism that live in the past

Gene Pool

all the genes in a population at one time

evolutionary adaption

an inherited characteristic that enhances an organism's ability to survive and reproduce in a particular environment

Survival of the fitest

darwinism,, process by which individuals that are better suited to their environment survive and reproduce most successfully; also called natural selection

Evolutionary species concept

identifies species in terms of their ecological niches, focusing on unique adaptations to particular roles in a biological community.

Law of supersition

sedimentary layers are deposited in a time sequence where oldest on bottom youngest on top

Half-life

the period of time in which half of a radioactive substance decays

Competition

the struggle between organisms to survive in a habitat with limited resources