Biology 3201 U3A: Evolution

Evolution

the relative change in genetic traits of populations that occurs over successive generations

Microevolution

Gradual change in allele frequencies in a population over time

Macroevolution

Large-scale evolutionary changes including the formation of a new species

Adaptation

a structure, behavior, or physiological process that helps an organism survive in a particular environment

Structural Adaptation

are physical features on an animal that have evolved over time to help them survive and breed

Behavioral Adaptation

are changes in behavior that certain organisms or species use to survive in a new environment

Physiological Adaptations

refers to the metabolic or physiologic adjustment within the cell, or tissues, of an organism in response to an environmental stimulus resulting in the improved ability of that organism to cope with its changing environment

Structural Adaptation Examples

camouflage, eagle claws, eagle vision

Behavioral Adaptations Examples

migration, hibernation, dormancy

Physiological adaptations examples

cold-water marine mammals dropping their heart rate during dives, temperature regulation in animals, anti-freeze in fish

Variation

A visible or invisible difference among some members of a population

Sexual Reproduction

a source of variation, parents pass down hereditary information to their offspring

Crossing over during meiosis

occuring in prophase I, homologous chromosomes, one from each parent, pair along their lengths, gene by gene. Breaks occur in the chromosomes, and they rejoin, trading some of their genes

Mutations

source of variation in populations, mutations happen continuously in the DNA of any living organism. They can occur spontaneously, when DNA is copied before a cell divides

Germ line mutation

mutation that occurs in sperm or egg and may be passed down to succeeding generations

Artificial Selection

selective breeding to obtain varieties of plants or animals with desired traits

Natural Selection

process through which populations of living organisms adapt and change

Stabilizing Selection

a form of natural selection that favors an intermediate phenotype and acts against extreme versions of the phenotype

Directional Selection

a form of natural selection that favours the phenotype at one extreme over the other

Disruptive Selection

A form of natural selection that favours the extremes of a range of phenotypes over intermediate phenotypes, and may eliminate intermediate phenotypes from the population

Sexual Selection

A special case of natural selection in which a particular phenotype improves an individual's chances of obtaining a mate

Industrial Melanism

an evolutionary effect prominent in several arthopods, where dark pigmentation has evolved in an environment affected by industrial pollution

Antibiotic Resistant Bacteria

bacteria that builds up resistance to antibiotics, allowing them to survive in infected bodies longer

horizontal genetic transfer

when types of bacteria not only pass down their genes when they reproduce, but can also transfer their own genes to cells in their generation

Extirpation

is the condition of a species that ceases to exist in a chosen geographic area of study, but continues to exist elsewhere.

Extinction

termination of a kind of organisms or of a group of kinds, usually a species. The moment is generally considered to be the death of the last individual of the species

Plato and Aristotle

believed that all life existed in a perfected and unchanging form

Georges-Louis Leclerc

French naturalist, noticed the similiarities between humans and apes and speculated they might have a common ancestor, suggested that earth was older than 6000 years

Mary Anning

unearthed the ancient remains of a prehistoric fish called Ichthyosaurus, a specimen that looked unlike any animal known to be living during her time. Made people question the idea that all living beings came to existence at the same time

Fossils

provided good evidence that many life forms of the past no longer existed

Georges Cuvier

developed paleontology, discovered each stratum is characterized by a unique group of fossil species. The deeper you go, the more dissimilar the species are from modern life. He found species appear and others disappeared over time, showing animals could become extinct

Paleontology

the study of ancient life through the examination of fossils

Revolutions

what Cuvier called catastrophic, natural events like floods and volcanic eruptions. Violent enough to have killed numerous species.

Catastrophism

based on Cuvier's ideas, the theory that changes in the earth' crust during geological history have resulted chiefly from sudden violent and unusual events

Charles Lyell

scottish geologist, proposed that geological process operated at the same rates in the past as they do today. Suggested Earth is more than 6000 years old, and that slow process can cause substantial changes over long periods of time

Principles of Geology

Charles Lyell's book that proposed earth's slow geological processes had an effect on the populations on earth

6000 years

before Lyell and Leclerc, how old people thought the Earth was

Histoire Naturelle

book that presented Leclerc's understandings about the natural world, including that humans and apes may have a common ancestor

Uniformtarianism

the theory that changes in the Earth's crust during geological history have resulted from the action of continuous and uniform processes

Jean-Baptiste Lamarck

french naturalist, proposed the "line of descent" in which a series of fossils led to modern species. Thought that species increased in complexity until reaching a level of perfection, came up with theory of acquired characteristics

Line of descent

Lamarck's theory, series of fossils led to a modern species.

Inheritance of Acquired Characteristics

Lamarck's idea that characteristics acquired during an organism's lifetime could be passed down to its offspring. This is not true, you do not gain skills your parents have or the traits they gained through use.

Charles Darwin

created the ideas of natural selection, and descent and modification. Modification occurs from long-term natural selection

HMS Beagle

English survey ship that Charles Darwin left England on

On the Orgin on Species

Darwin's book that proposed the theory of evolution

1. Present forms of life have arisen by descent and modification from an ancestral species

2. The mechanism for modification is natural selection working for long periods of time

Galapagos Finch Species

Darwin observed these, they looked similar yet distinct from one another and any finch species on continential south america.

Alfred Russel Wallace

another British naturalist, independently reached conclusions that were similar to Darwin's, theory of natural selection

Thomas Malthus

an economist who wrote the essay Principles of Population, stating that populations produced far more offspring than their environments can support and eventually will be reduced by starvation or disease

Darwin's Observations about rodents

rodents in South America were structurally similar to one another, but different from the rodents he observed on other continents. If all species were created at the same time, why weren't they equally spread all over the world

Darwin's observation of fossils

he found fossils in an area often bared resemblance to populations currently living in the region

coast of closest continents

finches and other animals that Darwin observed on the Galapagos Islands closely resembled animals he observed on the west coast of South America. This is common, animals on the ______ often have similarities, dating back to Pangea

Identical at first, but differences between islands

Finch species on the Galapagos Islands, all stemming from an ancestral species but each having their own adaptations

Darwin's breeding of dogs and pigeons

Darwin learned that sexual reproduction resulted in many different variations between within a species, leading him to believe something similar to selective reproduction can be found in nature.

Fossil Record

Remains or traces of past life preserved in sedimentary rock, which reveal the history of life on Earth

Index Fossils

Fossils that are known to be common during a particular time, and so indicate the age of the rock they are found in.

Fossils found in young rock

usually similar to the species that alive today rather than the species found in deeper and older layers of rock

Chronological order

the order fossils appear in rock layers, so older ancestors would be found in older rock and vice-versa.

Radiometric Dating

method of dating rocks and minerals that uses measurements of certain radioactive isotopes to calculate absolute age in years.

Transitional Fossils

fossils that show intermediary links between groups of organisms

Ancient Whales

Basilosaurus and Dorudon, had tiny hind limbs but led an entirely aquatic life

Ambulocetus

ancient whale ancestor that had heavier leg bones, scientists hypothesize that it lived on both land and in water

Archaeopteryx

show a transitional stage in the fossil record because this species had characteristics of both reptiles and birds. It had feathers like birds, but also teeth, claws, and a bony tail

Biogeography

the study of the past and present geographical distribution of a species

Geographically close environments

more likely to be populated by similar species than locations that are geographically separate but environmentally similar

Cacti

native to North, Cental, and South American deserts only, even though similar habitats exist in Australia and Africa.

Animals found on islands

closely resemble animals found on the closest continent, suggesting they evolved from mainland migrants and adapted to the environment of their home.

Fossils of the same species

can be found on the coastline of neighbouring continents. For example,, the Cynognathus can be found in Africa and South America

closely related species

never found in the same habitat

Comparative Anatomy

the comparative study of the body structures of different species of animals in order to understand the adaptive changes they have undergone in the course of evolution from common ancestors

all vertebrate forelimbs

contain the same set of bones, organized in similar ways

Homologous Structures

physical features with the same evolutionary origin and underlying structural elements, but may have different functions

Analogous Structures

Physical features that evolved separately but perform similar functions in different types of organisms. Functionally similar in anatomy, but does not mean the species is closely related

the wings of insects, birds, bats, and pterosaurs

similar in function, but not in structure. Bones support bird wings, but a tough material called chitin makes up insect wings

Convergent Evolution

Tendency among species that are not closely related to develop similar body plans when living under the same conditions

Vestigial Structures

Anatomical Features that no longer retain their function

Vestigial Structures are

homologous to functioning structures of other species

Embryology

the embryos of different groups of organisms exhibit similar stages of embryonic development

all vertebrate embryos

have paired pouches or out-pocketings of the throat. In humans, these develop into the ears and throat

develop into gills

fish and amphibian vertebrate pouches

molecular biology

developed as technologies to identify molecules such as DNA and proteins developed. Has come to support common ancestry and evolution through natural selection

chimpanzees

humans closest living relative, sharing almost all DNA other than an inverted section on chromosome 5

Speciation

the formation of new species

Transformation

a new species gradually develops as a result of mutation and adaptation to changing environmental conditions, and the old species is gradually replaced

evolution of mammoths

followed the transformation pathway. Ancestral mammoths lived 2.6 million-700 000 years ago, which then slowly evolved into the steppe mammoth that lived 700 000 to 500 000 years ago, into the woolly mammoth that lived 350 000 to 10 000 years ago

Divergence

adaptive radiation, one or more species arise from a parent species that continues to exist

Geographical Barrier

feature such as a mountain that physically separate populations and so prevents them from interbreeding

Biological Barrier

features of different populations that keep them reproductively isolated, even when the exist in the same environment

Reproductively Isolated

the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences

cichlids

a species of fish that speciated after a lake dried to just a few small pools of water. Once the water levels rose again, they were unable to mate with each other and had remarkable diversity between them

Prezygotic Barrier

a mechanism that blocks reproduction from taking place by preventing fertilization

Behavioral Isolation

biological barrier in which species-specific signals or behaviors prevent interbreeding with closely-related species

Ecological/Habitat Isolation

biological barrier in which different species live in the same general area, but use different habitats (like land/water), and so they rarely encounter each other

Temporal Isolation

Timing barriers that prevent species in the same habitat from interbreeding; species may mate or flower at different times of the day, in different seasons, or in different years

Mechanical Isolation

biological barrier in which closely related species have incompatible reproductive structures, and so cannot mate, or, in the case of plants, cannot be pollinated by the same species of pollinator

Gametic Isolation

Biological barrier, such as a chemical marker on an egg, that prevents eggs and sperm from different species fusing to form a zygote

Postzygotic Barriers

a mechanism that blocks reproduction after fertilization and zygote formation

Hybrid Inviability

a genetic incompatibility of interbred species that stops development of the hybrid zygote during its development

Hybrid Sterility

A biological barrier that exists between two species because, although they can mate and produce offspring, the offspring is sterile