Changes Over Time Sea Horse Reproduction Mule In

Changes Over Time

Sea Horse Reproduction

• Mule In its common modern meaning, a mule is the offspring of a male donkey and a female horse The term "mule" (Latin mulus) was formerly applied to the infertile offspring of any two creatures of different species. • The chromosome match-up more often occurs when the jack (male donkey) is the sire and the mare (female horse) is the dam. Sometimes people let a stallion (male horse) run with a jenny (female donkey) for as long as six years before she becomes pregnant. Mules and hinnies are almost always sterile (see fertile mules below for rare cases). The sterility is attributed to the differing number of chromosomes of the two species: donkeys have 62 chromosomes, whereas horses have 64. Their offspring thus have 63 chromosomes which cannot evenly divide.

Zorse • Zorse • A zorse or zebrula is the offspring of a zebra stallion and a horse mare; the rarer reverse pairing is sometimes called a hebra. It is a zebroid: this term refers to any hybrid equine with zebra ancestry. • The zorse is shaped more like a horse than a zebra, but has boldly striped legs and, often, stripes on the body or neck. Like most other interspecies hybrids, it is infertile. • Zebras, donkeys and horses are both members of the family equus -- equines. Equines can be crossbred to produce hybrids. They are all slightly different in genetic makeup, but still all equines. That is, horses have 64 chromosomes, zebra have between 44 and 62 (depending on species). Zorses can be male or female, but are sterile since their chromosome count is 63.

• Standard BIO 8 a-e The student will investigate and understand how populations change through time. Key concepts include: • a) evidence found in fossil records; • b) how genetic variation, reproductive strategies, and environmental pressures impact the survival of populations; • c) how natural selection leads to adaptations; • d) emergence of new species; and • e) scientific explanations for biological evolution.

Charles Darwin The Father of Evolution

History • • • Darwin’s World (1809 - 1875) Height of the British colonial period. Beginning of the Industrial Revolution. • New Ideas: – Taxonomy of Carolus Linnaeus – Lyell’s “Principles of Geology”

Binomial System of Nomenclature Carolus Linnaeus (1707 – 1778) Believed in the “Fixity of Species”

Charles Lyell • Father of Geology

Charles Lyell’s view of the process of formation of sedimentary rock

• Suggests that sedimentary rock is very old – therefore the species that are represented in this rock must also be old. • Most fossils are found in sedimentary rock. • Older fossils will be found below younger fossils.

Charles Darwin At the age of 22, he joined a 5 year expedition aboard the HMS Beagle to map the coast of South America

The voyage of the Beagle

Charles Darwin’s Theory of Evolution: 1. Members of a population have heritable variations. (Inheritance of traits)

2. In a population, more individuals are produced than the environment can support. They compete for food and shelter. (overpopulation- struggle for survival).

3. Some individuals have adaptive characteristics that enable them to survive and reproduce better than other individuals (survival of the fittest).

4. An increasing number of individuals in succeeding generations have these adaptive characteristics (natural selection)

Darwin described his theory in the form of a long essay which he called “On the Origin of Species”.

Concerned about the public’s response to his ideas (remember what happened to Galileo) Arranged to publish his work … AFTER HIS DEATH !!

Publication of “On The Origin of Species” in 1859

Charles Darwin At age 50 (1859) At age 65 (1874)

Charles Darwin Before publication After publication

• Through his observations made in the Galapagos Islands, Charles Darwin formulated a theory of how species change over time, called natural selection.

• Natural selection is governed by the principles of genetics. • The change in the frequency of a gene in a given population leads to a change in a population and may result in the emergence of a new species. • Natural selection operates on populations over many generations.

Evolution • A change in successive generations of organisms, due to random mutation and changes in the organisms’ surroundings

• Evolution takes place through a set of processes that include: – – mutation, adaptation, natural selection, extinction.

Mutation • Genetic mutations and variety produced by sexual reproduction allow for diversity within a given population. • Many factors can cause a change in a gene over time.

Mutation • Mutations are important in how populations change over time because they result in genetic changes to the gene pool.

• Mutations are inheritable changes because a mutation is a change in the DNA code

Mutation- a change in the DNA A mutation may result in a: 1. favorable change or adaptation in genetic information that improves a species’ ability to exist in its environment

Mutation- a change in the DNA 2. an unfavorable change that does not improve a species’ ability to exist in its environment.

Mutation- a change in the DNA 3. in a change in the genetic information that neither harms nor helps the species.

Adaptation • Adaptations are structures, functions, or behaviors that enable a species to survive.

Adaptation • Depending on the rate of adaptation, the rate of reproduction, and the environmental factors present, structural adaptations may take millions of years to develop.

Natural Selection • the survival and reproduction of the individuals in a population that exhibit the traits that best enable them to survive in their environment. • The Survival of the Fittest

Natural Selection • Populations produce more offspring than the environment can support.

Natural Selection • The unequal ability of individuals to survive and reproduce leads to the gradual change in a population, generation after generation over many generations.

Natural Selection • Organisms with certain genetic variations will be favored to survive and pass their variations on to the next generation.

• These five canine species evolved from a common ancestor through natural selection Jackal African wild dog Fox Thousands to millions of years of natural selection Ancestral canine Wolf Coyote

When humans choose organisms with specific characteristics as breeding stock, they are performing the role of the environment • This is called “artificial selection” Example of artificial selection in plants: five vegetables derived from wild mustard

Artificial Selection in Animals: Dog Breeding German shepherd Yorkshire terrier English springer spaniel Hundreds to thousands of years of breeding (artificial selection) Ancestral dog Mini-dachshund Golden retriever

The evolution of insecticide resistance is an example of natural selection in action Chromosome with gene conferring resistance to insecticide Additional applications of the same insecticide will be less effective, and the frequency of resistant insects in the population will grow Insecticide application Survivor

Extinction • no longer in existence; "the extinction of a species"

• If a species does not include traits that enable it to survive in its environment or to survive changes in the environment, then the species may become extinct.

Individuals die, a species becomes extinct.

• Individuals of a population exhibit a range of variations in a trait as a result of the variations in their genetic codes.

• The evidence for evolution is drawn from a variety of sources of data, including: – – – the fossil record, radiometric dating, genetic information, the distribution of organisms, anatomical and developmental similarities across species.

Fossil Record • Although there is not a complete record of ancient life for the past 3. 5 billion years, a great deal of modern knowledge about the history of life comes from the fossil record.

• The study of fossils provides strong evidence for evolution. Hominid skulls Petrified Trees

Ammonite casts Fossilized organic matter in a leaf

Scorpion in amber “Ice Man”

Distribution of species • Most marsupials live in Australia • This supports theory of continental drift.

Distribution of species

Geographic isolation can lead to speciation

Species • Organisms that can breed and produce FERTILE offspring.

Adaptive Radiation • where species all deriving from a common ancestor have over time successfully adapted to their environment via natural selection

Homologous Structures • Body parts in different organisms that have similar bones and similar arrangements of muscles, blood vessels, and nerves and undergo similar embryological development, but do not necessarily serve the same function; e. g. , the flipper of a whale and the forelimb of a horse.

Homologous Structures Human Cat Whale Bat

Vestigial Structures • Features that apparently serve no function in an organism and are allegedly holdovers from an evolutionary past. Such features, though no longer useful, are presumed to have been useful in ancestral species.

EX. : Wings in flightless birds

EX. : appendix in humans, whale pelvis, tiny snake pelvic and limb bones, and the eyes in cavedwelling salamanders and fish that are completely blind.

Developmental Similarities • Many species have very similar embryonic development. • The embryo of a chicken, a pig, and a fish are almost identical at certain points in their development.

• Stephen Jay Gould’s idea of punctuated equilibrium proposes that organisms may undergo rapid (in geologic time) bursts of speciation followed by long periods of time unchanged. • This view is in contrast to the traditional evolutionary view of gradual and continuous change