Biology Exam 1

Theodosius Dobzhansky

1831, HMS Beagle, 5 year voyage

• 1. Species change over time.
• 2. Divergent species share a common ancestor.
• 3. The process that produces the change is natural selection.

• Naturalist
• Proposed similar explanations for natural selection
• Paper from Darwin and Wallace published in 7/1/1858 to Linnean Society of London

• The Origin of Species
• Published 1859

• Economist
• Published An Essay on the Principle of Population in 1838
• Populations of all species have potential for rapid increase but it does not occur

The process by which characteristics that are useful evolve

Evolved over time to have colors that coordinate with their environment

A group of individuals of the same species that live in the same area and interbreed. Populations adapt to their environment.

Segment of DNA that codes for a trait

Different form of a gene

The physical expression of a gene. I.e eye color

The allele combination of a trait. I.e Bb.

Both alleles the same. BB. bb.

Alleles different. Bb

Local interbreeding groups

• Model in which allele frequency does not change. Null hypothesis.
• -Mating random
• -Population size infinite
• -No gene flow-no in or out of population
• -No mutation
• -Natural selection not a factor

• Results from random changes in allele frequencies.
• Can influence frequencies of alleles that do not effect survival and repro.

Population reduced to small number of individuals

• Directional-Shifts toward one extreme of traits and away from the other extreme
• Disruptive-Shifts towards both extremes and away from the average.
• Stabilizing-Shifts toward average and away from extremes.

Natural selection that favors traits that improve repro

• 1940
• Biological species concept:
• Species are groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other groups.

• Habitat-Live separately
• Temporal- Time of breeding is different
• Behavioral-Different mating style
• Mechanical-Organs incompatible
• Gametic-Gametes do not survive

Hybrids cannot reproduce further

Population is separated by physical barrier. They reintegrate but can no longer reproduce with each other.

• Established nomenclature system
• Genus species

Rapid diversification occurred during this period

• Domain
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

Have FUR and MAMMARY GLANDS

• Live in extreme environments
• Methanogens: produce methane
• Thermoplasma: no cell wall, thermophili
• Sulfobus: live in sulfur springs, HOT, ACIDOTIC

• Spherical
• Rod Shaped
• Spiral

Eukaryotes that are neither plants, animals, or fungi

• Mobile-Cillia, flagella
• Amoeboid motion-pseudopods
• Imotile-stationary

Reproduction, most are asexual and sexual

Secrete digestive enzymes and absorb nutrients

Absorb nutrients from dead organic matter

Absorb nutrients from living host

Live in intimate association with another organism that benefits both organisms

Fungi and photosynthetic organism, mutualistic relationship

• Xylem-Takes water and minerals up from soil
• Phloem-Takes products to roots for storage

• Prehistoric fish that was thought to be extinct.
• Rediscovered in 1938

• Existed before reptiles
• Reproduction tied to water
• Skin must stay moist
• Can live on land
• External or internal fertilization

• Eukaryotic
• Multicellular
• Heteroptroph-Energy from food
• Internal digestion
• Movement

• Can survive on land away from water
• Better lungs
• Hard shell eggs
• Internal fertilizaton
• Scaly skin
• Kidneys secrete concentrated urine to prevent dehydration

• Storage
• Absorption
• Anchor

Transports water and minerals

Outer covering of plant

Carries out photosynthesis and provides support

• Numerous in young plants with thin flexible walls
• Photosynthetic with many chloroplats
• Store starch and lipids

• Thick cell walls
• Elongate shape
• Flexible, but provide support

• Have thickened secondary walls
• Provide strong support
• Fibrids and sclerids

• One cotyledon
• Veins parallel
• Scattered vascular tissue
• Fibrous roots
• Pollen with one opening
• Floral organs in multiples of three

• Two cotyledons
• Netlike veins
• Vascular tissue organized in ring
• Main root
• Pollen with three openings
• Floral organs in multiple of four or five

Vascular plants with seds enclosed in modified leaves called carpals

• Roots
• Stems
• Leaves

Stems and leaves, photosynthesis

Roots

Explains movement of water up stem to leaves and out

Flowers contain the sex organs