Tomorrow's Course (Probably)

Monday~ Monday~ Welcome back to Monday !!! Say hello to Mr. Monday~

Yesterday I had a graduate party in my department, maybe I'll post about it later. But first I 'll post about my prediction (#ngeh). Yes, like just I said before and it also written in the tittle. Tonight I 'll post about tomorrow's course. Tomorrow I will have 'animal's development' course. So lets get start !

Embryology was the formal term that used to explain a progressive development in organism. That term have different meaning in each animal classes. For the example, amphibian used that term from the fertilization until it has metamorphosed. Another example, Aves use the term until the eggs hatched (since Aves won't metamorphosed).

Basically there is two of old scientist's arguments about embryology.

Karl Ernst von Baer's Law

"Very simple but little difficult to be memorized"

1. General characteristics of the group to which an embryo belongs develop before special characteristics.
2. General structural relations are likewise formed before the most specific appear.
3. The form of any given embryo does not converge upon other definite forms but, on the contrary, separates itself from them.
4. Fundamentally, the embryo of a higher animal form never resembles the adult of another animal form, such as one less evolved, but only its embryo. 

Cell Lineage Mechanism

Pangenesis (Darwin)

Genetic material named 'Gemulla' formed by somatic cell which transmigrated into gammete cell (generative part of human cell).

Germplasm(Weissmann)

Germplasms is a collection of genetic resources (genetical unit) for an organism. Somatic cell are the result of differentiation process from gamete cells.

Period of embryonic development

1. Preparation stage

gamete cell's development in the gonads

2. Fertilization stage

fusion of male gamete cell (sperm) and female gamete cell (ovum)

3. Cementation stage

Division of the cell without significant growth, producing a cluster of cells that is the same size as the original zygote, is called cleavage. At least four initial cell divisions occur, resulting in a dense ball of at least sixteen cells called the morula. The different cells derived from cleavage, up to the blastula stage, are called blastomeres. The cleavage can be total (holoblastic) or partial (meroblastic) depending on the amount of yolk.

4. Cell shell formation 

 

Ectoderm - Nervous system, skin, organ on the entire surface of the skin, etc

Mesoderm - Bone, Muscle, Blood, Blood vessel, gamete cell, etc

Endoderm - Digestive cell, respiratory cell, lung, etc 

5.  Organogenesis
Each cell shell will a complex system that consist of cells with similar characteristic

6. Growth and Differentiation
Cell will growth and differentiate by it function.

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Thank you for reading my post. See yaa next time, fellas ^_^

 

Tuesday's course, Animal Taxonomy 1 !!

In animal taxonomy there are two ways to divide an animal into different classes. The old ones is with Apparent Differences method and  the newest ones with Reproductive Isolation method. Both method are can be used to indentify an animal classes.

Apparent Differences

Taxonomy method that use an animal apparent which can be seen or can be observed. Such as animal morphology , including external and internal morphology and animal physiology. Animal referred in one species if it has less of differences. There are some case that CAN NOT be solved with apparent differences method.  e.g. case between Alder flycatcher with Willow flycatcher.

Alder flycatcher (Empidonax alnorum )

Willow flycatcher (Empidonax traillii )

Both Alder flycatcher and Willow flycatcher are look like the same. Since they have the same morphology. They only can be distinguished by their sound (tweet). So they can’t be identified by apparent differences method easily. More description about their difference can be checked here

Reproductive Isolation

Taxonomy method which observe the results of breeding between two organisms.  An animal can be called in one species when it could produce fertile offsprings. Just like previous method There are some case that CAN NOT be solved with reproductive isolation method. e.g. case between Baltimore oriele with Bullock's oriele.

Baltimore oriole (Icterus galbula)

Bullock's oriole (Icterus bullockii)

Both Baltimore oriele and Bullock's oriele have different morphology but they can be bred and produce fertile offspring . So they can be identified easier than use reproductive isolation method. The reason why they could produce a fertile offsprings is because of their DNA and Molt timing.

• Molt Timing: Baltimore Orioles typically molt their plumage in summer after breeding but before migrating. Bullock's Orioles molt during migration and on their wintering grounds. One hybrid was found on its wintering grounds undergoing a molt, as Bullock's normally do, but it was molting out of brand new feathers! It was molting a second time after apparently already molting on its summer grounds. Molting takes a LOT of energy. Ornithologists believe that perhaps one reason why oriole hybrids don't increase is because they don't survive or reproduce as well as pure Baltimore and Bullock's Orioles do thanks to that wasted energy molting twice a year
• DNA: Recent studies of mitochondrial DNA (the DNA in the mitochondria of cells, which many scientists use to show relationships among various animals) show the Baltimore and Bullock's Orioles are not even very closely related! The Baltimore Oriole shows more genetic similarities to the Altamira Oriole (which lives in Mexico, northern Central America, and a tiny part of Texas) and especially to the Black-backed Oriole (from Mexico). Bullock's Oriole is more closely related to the Streak-backed Oriole (from Central America, Mexico, and rarely southern Arizona and California).

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Generaly, from today's lecture I catch a conclusion that Reproductive Isolation method is more accurate than the Apparent Differences method to identify the animal origin of the most species. Even In some case, there is a miss direction between reproduction isolation and apparent differences. 

Thank you so much for wasting your time here to read my post. I really appreciated your presence.
See yaa next time, fellas~ ^_^