Biological Species Concept and Hybridization

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Questions and Answers

What defines a species according to the biological species concept?

A group of organisms that share similar habitats

A group of organisms that can breed and produce sterile offspring

A group of organisms that can breed and produce fertile offspring (correct)

A group of organisms that exhibit identical traits

What is the morphological species concept based on?

Shared evolutionary history

Shared physical form and inner structure (correct)

Shared behaviors and interactions within a habitat

Shared genetic material among organisms

What happens to genetically identical organisms, like monozygotic twins, as they develop?

They develop identical physical traits

They acquire differences through mutations and environmental influences (correct)

They remain genetically identical throughout their lives

They do not experience any form of variation

Which of the following is NOT a rule for binomial nomenclature?

Genus name is italicized Signup and view all the answers

What is a genus in the context of biological classification?

A taxonomic rank that is above species Signup and view all the answers

Which of the following statements about species is false?

All species have identical characteristics Signup and view all the answers

What does the term 'binomial' refer to in taxonomy?

The two-part naming system for species Signup and view all the answers

Why is variation among organisms important in biology?

It leads to the classification and naming of species Signup and view all the answers

What does the presence of fertile offspring like Horse 3 indicate about Horses 1 and 2?

They are the same species. Signup and view all the answers

What defines a mule in terms of species classification?

An infertile hybrid of a horse and a donkey. Signup and view all the answers

Which of the following is considered a challenge to the biological species concept?

Some species can hybridize in captivity. Signup and view all the answers

What is the most significant outcome of speciation?

Populations develop recognizable differences. Signup and view all the answers

How can two populations be considered the same species despite rarely interbreeding?

They have a common ancestor. Signup and view all the answers

Which statement is true about the divergence of non-interbreeding populations?

Recognizable differences may gradually accumulate over time. Signup and view all the answers

What may complicate the identification of species in rapidly speciating populations?

The occurrence of interspecific hybridization. Signup and view all the answers

Which of the following is a key aspect of the biological species concept?

Species are groups of organisms capable of interbreeding. Signup and view all the answers

What is the diploid chromosome number for humans?

46 Signup and view all the answers

Which of the following statements about chromosome number changes is true?

Chromosome number rarely changes, potentially for millions of years. Signup and view all the answers

How are chromosomes classified when creating a karyotype?

By their banding patterns, size, and centromere position. Signup and view all the answers

What is the haploid chromosome number that represents the sex cells in humans?

23 Signup and view all the answers

Which hypothesis relates to the formation of human chromosome 2?

It was formed from the fusion of two ancestral chromosomes. Signup and view all the answers

What type of cells undergo division to study chromosomes for karyotyping?

Somatic cells Signup and view all the answers

Why do diploid cells have an even number of chromosomes?

They result from the fusion of haploid cells. Signup and view all the answers

What are the characteristic chromosome types in a species collectively called?

Karyotype Signup and view all the answers

Which statement accurately describes the relationship between the long arm of chimp chromosome 13 and human chromosome 2?

The banding pattern of chimp 13 is very similar to the long arm of human 2. Signup and view all the answers

What is predicted to be found in the region where the fusion of chimp chromosomes is hypothesized to have occurred?

A non-functional telomere still present. Signup and view all the answers

What does the presence of remnants of a second centromere in chromosome 2 suggest?

The second centromere derives from chimp chromosome 13. Signup and view all the answers

Which statement reflects the strength of the evidence regarding the fusion of chimp chromosomes in the evolution of human chromosome 2?

Significant banding patterns from both chimp chromosomes 12 and 13 are found on human chromosome 2. Signup and view all the answers

What comprises the genome of an organism?

All the genetic information contained in the organism's DNA. Signup and view all the answers

What causes diversity within a species?

Alternative forms of genes known as alleles. Signup and view all the answers

Which of the following statements about alleles is correct?

Alleles usually differ by a few bases. Signup and view all the answers

What is generally true about the genes of members within the same species?

They possess the same genes in the same sequence on each chromosome. Signup and view all the answers

What are single-nucleotide polymorphisms (SNPs)?

Positions in a gene with multiple possible base types. Signup and view all the answers

How many SNPs are typically found in one individual human?

About 4,000-5,000. Signup and view all the answers

Why do larger genomes not necessarily contain more functioning genes?

They have larger amounts of non-functional DNA. Signup and view all the answers

Which organism has the largest known genome size?

Paris japonica. Signup and view all the answers

What is the typical unit used for measuring genome size?

Base pairs. Signup and view all the answers

What does the C-value represent in genome size measurement?

The DNA content of a haploid cell. Signup and view all the answers

What is the impact of whole genome sequencing becoming faster and cheaper?

It has enabled the sequencing of thousands of species. Signup and view all the answers

Which statement about the variation in genomes is true?

Variation within a species is much smaller than variation between species. Signup and view all the answers

Study Notes

Species Concept and Hybridization

Horse 3 is fertile, indicating that Horse 1 and Horse 2 belong to the same species.
Mules, hybrids of horses and donkeys, are infertile, showcasing a clear distinction between these two species.
Hybridization occurs in captivity, as evidenced by ligers (male lion x female tiger) and tigons (male tiger x female lion).

Challenges of the Biological Species Concept

The biological species concept defines species based on the ability to breed and produce fertile offspring.
Rapid speciation, such as in certain conifer genera, complicates species identification due to interspecific hybridization.

Population Divergence and Speciation

A population is a group of the same species organisms sharing the same location and time.
Non-interbreeding populations can evolve independently, leading to genetic divergence and potential new species formation.
Speciation is typically a gradual process characterized by the accumulation of genetic differences.

Genetic Variation Among Organisms

No two individuals are genetically identical; monozygotic twins exhibit variations from environmental factors and mutations.
Variations among organisms form the foundation for biological classification.

Morphological Species Concept

The term "species" reflects a group of organisms that share defining physical traits, a concept introduced by Carl Linnaeus.
Morphological characteristics serve as the basis for identifying species.

Binomial Nomenclature

The binomial system assigns species names using a two-part format: genus (capitalized) and species (lowercase).
Example: The coyote is named Canis latrans.
After initial mention, species names can be abbreviated (e.g., C. latrans), typically italicized.

Chromosome Variation

Different species display distinct chromosome numbers; for example, humans possess 46 chromosomes while chimpanzees have 48.
Chromosome numbers can increase or decrease through fusion or splitting during evolution.

Karyotyping Techniques

Karyotyping involves analyzing chromosomes from dividing cells, creating karyograms based on banding patterns, size, and centromere positions.
Human somatic cells contain 46 chromosomes, while closely related primates have 48, highlighting our evolutionary relationships.

Evidence for Chromosome Fusion

The similarities between human chromosome 2 and chimpanzee chromosomes 12 and 13 point toward a potential fusion event in human evolution.
Characteristics such as banding patterns and remnants of additional centromeres provide strong evidence for chromosome fusion.

Genome Diversity Within Species

An organism's genome encompasses all its DNA, containing both genes and non-functional DNA.
Genetic diversity within a species is primarily due to allele variations, including single-nucleotide polymorphisms (SNPs).

Comparative Genome Sizes

Genome sizes vary significantly across species, with the human genome being approximately 3,080 million base pairs in size.
Organism genome sizes: Paramecium tetraurelia (27 Mb), Honey bee (217 Mb), Chimpanzee (3,175 Mb), Woodland plant (150,000 Mb).

Whole Genome Sequencing

Whole genome sequencing determines an organism's complete DNA sequence, a process that has evolved to become faster and more affordable since its inception in the 1990s.
Advances in genome sequencing technology have enabled the study of thousands of species, enhancing biological research and understanding of genetic diversity.

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Description

This quiz explores the complexities of species concepts and hybridization, focusing on examples such as horses, mules, and ligers. It delves into challenges with identifying species due to rapid speciation and genetic divergence. Test your knowledge on how populations evolve and the criteria that define a species.