Fundamentals of Biology. Chapter 4

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1 Fundamentals of Biology Chapter 4

2 Modes of Reproduction Asexual reproduction Does not involve mating of two individuals Young are produce by a single parent organism The young produced are genetically identical to the parent

3 Modes of Reproduction Examples of Asexual Reproduction Fission the splitting of one organism into two smaller organisms of equal size Budding the organism develops buds (small clones) that eventually break off and become another organism Vegetative reproduction a plant reproduces new individuals by sending an underground stem (rhizome) sideways from which new plants will sprout

Modes of Reproduction Sexual reproduction Normally involves two individuals Parent individuals produce gametes (eggs or sperm) that unite to

4 Modes of Reproduction Sexual reproduction Normally involves two individuals Parent individuals produce gametes (eggs or sperm) that unite to produce a new, genetically unique individual Ovaries are the organs that produce eggs Testes are the organs that produce sperm Obelia geniculata or Sea Fur

For broadcast spawning to be effective, millions of gametes must be released into the water at roughly

5 Modes of Reproduction Many marine organisms release their eggs and sperm directly into the water, this is known as broadcast spawning. For broadcast spawning to be effective, millions of gametes must be released into the water at roughly the same time to ensure fertilization will occur Many broadcast spawning species time the release of their eggs to tides, moon phase, water temperature, etc. to ensure success Coral

6 Modes of Reproduction Other marine organisms rely on internal fertilization, where a copulatory organ is used to insert sperm directly into the female s reproductive tract This method requires contact between parent individuals, but less gametes are required for success

7 Modes of Reproduction Hermaphrodites individuals that have male and female reproductive tissues either simultaneously or at different phases during the life.

Protogyny- an individual spends the first portion of the life as a functional female then

8 Examples hermaphrodites: Protandry- an individual spends the first portion of the life as a functional male then becomes a female later in life after some cue initiates the change Protogyny- an individual spends the first portion of the life as a functional female then becomes a male later in life after some cue initiates the change Horseshoe Worms (Phoronida) Sea Snail

9 Evolution and Natural Selection Evolution is defined as a change in the genetic makeup of a population over time In the wild, any genetically derived traits (such as faster swimming or above-average intelligence) can give one individual survival advantage over others in his/her population.

10 Evolution and Natural Selection These advantages can be translated into reproductive advantage as well. If one organism is better survivor, more of their gametes will make it into the next generation in a population. Those individuals that are less advantaged may not survive to reproduce or will reproduce less. This is known as natural selection.

11 Evolution and Natural Selection Natural selection therefore strengthens the gene pool of a species by eliminating less advantageous traits through lack (or reduction) of reproductive events in these individuals.

12 Taxonomy Taxonomy is the science of classifying and naming organisms. This classification is done by a variety of methods including DNA and protein analysis, comparing embryos, looking at the fossil record and comparing internal and external body structures.

13 Taxonomy Taxonomy uses several levels of classification shown below from the largest (most species inclusive) to the smallest (only one species): Domain Kingdom Phylum Class Order Family Genus Species

15 Phylogenetics Phylogenetics is defined as the study of evolutionary relationships (relatedness) in organisms. Biologists may use many factors to determine the relatedness of organisms such as structure, reproductive patterns, embryological or larval development, fossils, behavior or DNA/RNA.

Asexual Reproduction

Asexual Reproduction Only one parent is involved in asexual reproduction. The offspring is genetically identical to the parent. The offspring inherits all of its traits from one parent. Therefore, the