Friday, June 29, 2012

Biological Science 15 (Evolution)


Day 26: 

Spoiler Alert 1: Evolution Exists
Spoiler Alert 2: Evolution, Not Tremendously Exciting
Evolution [1]

A. Evolution

The change of amount of alleles of genes within a population (yawn).

1. Natural Selection
The individuals that have traits that are extremely undesirable, don't survive to breed, so there are less of those undesirable traits as time goes on. Ex. Babies with hearts on the outside of their body.

A. Fitness Concept
From an evolutionary perspective reproduction is essential so, fitness means ability to live, mature and reproduce successfully. Homosexuals do not have high fitness from this perspective, though it is surprising how many homosexuals still produce children.

B. Selection by Differential Reproduction
Tendency towards reproduction is a trait that spreads, because individuals with a tendency not to reproduce do not spread their genes.

C. Concepts of Natural and Group Selection
Natural selection means those that survive to reproduce are "selected" to keep existing. Group selection explains Lemmings. In interest of group survival, the individual Lemming will migrate away (possible to their death) so the rest of the Lemmings have food.

D. Evolutionary Success as Increase in Percent Representation in the Gene Pool of the Next 

If an allele increases over time it is a "success." Diversity is actually a positive thing, that prevents disease. If it was good for an allele to increase to 100%, then it would have already happened. Gene flux is healthy... 

2. Speciation
Close entities are termed a species. Like humans, we are the Homo sapiens sapiens species.

A. Definition of Species
A species can interbreed, and naturally produce viable offspring (whales and dolphins breed, but their offspring are sterile).

B. Polymorphism
Different alleles. Red hair, brown hair, black hair. Blue eyes, amber eyes, grey eyes ext.

C. Adaptation and Specialization
Adaptation is the change in a population caused by natural selection. Specialization is adaptation to fit a certain niche (tall necks to eat leaves on tall trees).

D. Concepts of Ecological Niche, Competition
A niche is the place, food and resources that a species lives in and competes to occupy. Specialization allows a niche to be used by multiple species without competition. Ex. If a gas station and a restaurant are on the same corner they both use the corner without competing.  If two species use different niches they do not compete, if they use the same niche they do compete. Ex. If a Brazilian Jujitsu Gym and a Japanese Jujitsu Gym are on the same corner they compete for students, if they are in different areas they don't compete for students.

E. Concept of Population Growth Through Competition
Population growth slows down as food is less plentiful or due to competition for other resources like land or water. When a species is competing for food, members may begin to occupy different niches and become different species (like Darwin's Finches).

F. Inbreeding
Mating of relatives is known as inbreeding. Inbreeding decreases genetic diversity, making homozygotes more common (resulting in much higher risk of recessive diseases).

G. Outbreeding
Mating of non-relatives increases diversity and heterozygosity.

H. Bottlenecks, Genetic Drift
Bottlenecks are severe reductions of population size (thus genetic diversity). This happened to cheetahs, now they are practically clones. Genetic drift is random change (not selection) in allele frequency. When the population shrinks genetic drift is more pronounced.

I. Divergent, Parallel, and Convergent Evolution
Divergent (going different ways) evolution describes two species that used to be the same, but grew apart (producing homologous structures). Ex. food and healthy food were the same thing in the 1900s, but unhealthy changes were made to food and now food and healthy food are two separate things. Parallel (going the same way) evolution, the species were the same, grew differently, but now are staying similar and evolving in the same direction. Ex. Pop and country music have the same ancestor, they grew differently, but now they are not much different and headed in the same direction. Convergent evolution describes two species from different backgrounds that are becoming more similar. Ex. Cave animals all tend to loose color and vision.

J. Symbiotic Relationships
  • Parasites, do not have a symbiotic relationship, one species benefits to the detriment of the other.
  • Commensalism, do not have a symbiotic relationship, one species benefits.
  • Mutalism is a symbiotic relationship, both species benefit.

I. Parasitism
The host is harmed, the parasite benefits. Like tape worm, which takes nutrients from the host, causing damage and loss of nutrients.

Cestodes: Tape Worm [2]

II. Commensalism
The moss on tree is usually commensalistic. The tree allows the moss to have sunlight and a growing surface, but there is no benefit to the tree.

Giant Moss Trees [3]

III. Mutualism
The Famous Mutualism of Clownfish and Sea Anemones: the Clownfish fight off Butterfly Fish and the Sea Anemones protect the Clownfish from other predators. 

"I got your back Clownfish." "Good looking out Sea Anemone." [4]

3. Relationship Between Ontogeny and Phylogeny
Ontogeny is development during a lifetime of an individual. Phylogeny is the development of a species throughout evolutionary time. The human embryo goes through phases showing our phylogeny. We have gills, a notochord, segmentation, and flipper hands and feets, before we grow into our more familiar forms. 

Human Six Weeks Old [5]

4. Evolutionary Time as Measured by Gradual Random Changes in Genome
The molecular clock concept is that: random changes (drift) occur that are not caused by natural selection, measuring these changes tells how long ago two species diverged.

5. Origin of Life
Organic molecules created in the atmosphere shot out of the sky by a lightning bolt fell into the primordial ocean. Proved to be possible by Urey-Miller's experiment (they had gas, a spark and water in a closed system and the system turned pink and grew amino acids). [6]

Gas + Spark + Water -> Life As We Know It

RNA formed. RNA became enveloped. Anaerobic heterotrophs existed first (there was no oxygen or light), then anaerobic autotrophs started photosynthesizing (creating oxygen), last the aerobs evolved because there was now oxygen. Eukaryotes evolved by engulfing small mitochondria or chloroplasts. [7]

B. Comparative Anatomy

The primitive vertebrae defines humans as chordates, the advanced vertebrae as vertebrates.

1. Chordate Features
The phylum chordate has a notochord (backbone), pharyngeal pouches (cheeks), brachial arches (forming gill slits).

A. Notochord
The notochord is a primitive spine, not yet made of bone.

B. Pharangeal Pouches, Brachial Arches
Together pharangeal pouches and brachial arches form gill slits (which rare people retain).

C. Dorsal Nerve Cord
The dorsal (on the back) nerve cord forms the spine and the brain.

2. Vertebrate Phylogeny (Vertebrate Classes and Relations to Each Other)
The group vertebrate have spines. 

Vertebrates start with fish:

  • Agnatha (jawless): eel-like.
  • Condrichthyes: like sharks and rays having jaws and skeletons (of cartillage).
  • Osteichthyes (bony): feeder fish having a bony skeleton.
  • Amphibians: the bony skeleton was strong enough to support weight on land.
  • Reptiles: can go away from water (without drying out), lay eggs.
  • Mammals: milk, hair and heterodontic teeth. AND Birds: still lay eggs, feathers, beaks.  [7]

Foot Notes:
1. Gomez, R. Evolution. Drawing. [Online]. 2012. (retrieved Jul 03, 2012)

2. Tape Worms Attached to Stomach Wall. Photograph. Ewwwww! My Pet Has Tape Worms! [Online]. 2009. (retrieved Jun 29, 2012).

3. Giant Moss Tree. Photograph. Pics of Trees. [Online]. (retrieved Jun 29, 2012).

4. Clown Fish and Sea Anemone. Photograph. Christian Brothers University. [Online]. (retrieved Jun 29, 2012).

5. Human Six Weeks Old. Photograph. Precious Moments After "I Do."  [Online]. Feb 13, 2012. (retrieved Jun 29, 2012).

6. Miller-Urey Experiment. Wikipedia. [Online]. Jun 27, 2012. (accessed Jul 03, 2012).

7. Evolution. [Online]. 2008. (accessed Jun 29, 2012).

1 comment:

  1. i would like to know your opinion on the Evolution process as fully described in the bible in Genesis :!/notes/the-greatest-story-ever-told-retold/the-evolution-in-full-process-in-the-bible/321274041311874