新坑來(lái)啦！遺傳、進(jìn)化與生態(tài)學(xué) Genetics, Evolution, and Ecology. 這一部分的內(nèi)容是傳統(tǒng)大學(xué)的第二門(mén)生物課，即 General Biology 2。這門(mén)課理論上建議在閱讀完文集的第一部分的內(nèi)容之后再開(kāi)始學(xué)習(xí)，但基礎(chǔ)不足的朋友也可以嘗試閱讀喔~

這一部分的主要內(nèi)容均來(lái)自 Prof.?Angela J. Roles 的課程，因此本文集的這一部分均不會(huì)標(biāo)記為原創(chuàng)。但由于文本來(lái)源不清晰，UP主還是一個(gè)字一個(gè)字碼出來(lái)的文章，本文禁止非授權(quán)的轉(zhuǎn)載，謝謝！

Lesson 1: The Diversity of Life & Classification

[1] Biodiversity Hierarchy

Genetic diversity: molecular, organismal, and population;

Species diversity: populations and communities;

Ecosystem diversity: communities, landscapes, and biomes.

Understanding the diversity and unity of life:

“Nothing in biology makes sense except in the light of evolution.”

- Theodosius Dobzhansky, 1964

????What do we mean by diversity? Why is there diversity?

“The diversity is intelligible as the outcome of adaptation of life to different environments, or, [...] to different ecological niches.”

????What do we mean by unity? Why is there unity?

“The unity is understandable as a consequence of common descent and of universal necessities imposed by common materials.”

????Together, evolution, ecology, and genetics address these questions.

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[2] Classification

- Pre-historic cave paintings

Humans have recognized & valued diversity for millennia.

Early human depictions of animals (30,000 years ago)

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-?Aristotle’s scala naturae (~330 BCE)

Scala naturae translates as ‘ladder of nature’, aka the ‘great chain of being’.

The scala naturae classifies all beings from inanimate (non-living, lacking a soul) to animate (living, possessing a soul). Hierarchical, moving from “l(fā)ess perfect” to “more perfect”.

- Linnaean classification (1700s)

?In the Systema?Naturae?(1758), Carolus Linnaeus (aka Carl von Linn′e)?described a three kingdom system: Animals, Vegetables, and Minerals.

- Nested hierarchical system: each Kingdom contains Classes which contain?Orders which contain Genera (the plural of Genus) which contain?Species which contain Varieties;

-?Organisms are grouped by similarity in appearance (morphology).

- Binomial nomenclature

?Linnaeus also systematized the binomial nomenclature we use today;

?A taxon’s scientific name is simply the genus (capitalized and italicized)?followed by the species epithet (italicized but not capitalized);

?When referring to a particular species, you must always give both genus?and species names. But you can refer only to a genus, or to any rank?above genus (e.g., kingdom).

- Modern classification

?The current system of classification we use is modified from the?Linnaean system and aims to reflect common ancestry. We retain the?use of binomial nomenclature;

?The current system adds the ranks of domain, phylum, and family.

What does hierarchy signify, in the modern system?

????All organisms in the same group share?a common ancestor.

????Example: gorillas and?humans are both in the Order?Primates.

?????Considering species the lowest rank, higher ranks include more different species?and generally are older in terms of evolutionary age.

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Thinking Question

We’ve just considered how the way people have chosen to describe diversity?in the natural world has changed across time:

?Pre-historic cave paintings (30,000 years ago)

?Aristotle’s scala naturae (330 BCE)

?Linnaean 2-kingdom, hierarchical classification (1700s)

?Modern 3-domain, hierarchical classification system (since the 1990s)

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Questions to think about:

?For each era/method, how are groups defined? Why? What are the implications of belonging to one group versus another?

?What is similar/different among these systems?

?What may have changed over time in the implied values of each system?