L2: MODERN CONCEPTS IN UDNERSTANDING EVOLUTIONARY RELATIONSHIPS

Primordial Soup Theory

Suggest that life arose in a warm, shallow sea rich in organic molecular often referred to as the ___. These molecules formed through chemical reactions eventually combined to form self-replicating organisms

Alexander Oparin & JBS Haldane

Came up with primordial soup theory

Deep Sea Vent Theory

Proposes that life originated in hydrothermal vents deep in the ocean. The heat and minerals from these vents provided a suitable environment for the formation of organic molecules and the development of early life forms.

Cindy Van Dover

Came up with deep sea vent theory

Panspermia Theory

Suggests that life originated elsewhere in the universe and was transported to Earth on meteorites or other celestial bodies

Helmholtz et al.

Came up with panspermia theory

RNA World Hypothesis

proposes that __ a molecule capable of both carrying genetic information and catalyzing chemical reactions was the first self-replicating molecule on earth

Walter Gilbert

Came up with RNA world hypothesis

Carrying genetic material and Catalyzing chemical reactions

Two characteristics of the first self-replicating molecule on earth

Clay World Hypothesis

Suggests that ____, with their catalytic properties played a crucial role in the origin of life. They could have provided a surface for the assembly of organic molecules and the formation of early replicating systems

Graham Cairns-Smith

Came up with clay world hypothesis

morphological variation, convergent evolution, cryptic species, transitional forms, lack of fossil evidence. hybridization, parasitic lifestyles, rapid evolution

Problems encountered in classifying organisms (8)

Convergent Evolution

happens when unrelated species independently develop similar traits to live in similar environments (like sharks and dolphins)

Cryptic Species

Refers to two or more distinct species that are classified as a single group because they look almost identical in physical appearance

Transitional Forms

They display a mosaic of old and new characteristics, illustrating how major groups of plants and animals gradually evolved over time.

Hybridization

The interbreeding of individuals from two distinct species, subspecies, or divergent populations. This process combines genetic material from different lineages, which can create novel traits, drive rapid adaptation, or lead to the birth of entirely new hybrid species.

Morphological, molecular, ecological, behavioral data

This is what scientists use to overcome the challenges in classifying invertebrates accurately (4)

Monophyletic Group or Clade

• Ideal because they accurately represent evolutionary relationships

• a collection of organisms that includes a single common ancestor and all of its descendants.

Paraphyletic Groups or Paraphyton

• A biological grouping that includes a common ancestor and some, but not all, of its descendant lineages

• Exclude some descendants of a common ancestor

Polyphyletic Group

• A set of organisms that are grouped together based on shared physical traits or functions, but do not share a recent common ancestor.

• Include unrelated organisms based on superficial similarities

Cladistic vicariant biogeography, phylogeny, model-based biogeography

Approaches in understanding and analyzing species phylogeny and biogeography (3)

Cladistic Vicariant Biogeography, patterns, dispersal

• Starts with an area cladogram, tree in which taxon names are placed by their places of origin

• Good fi all taxa involved are endemic

• More interested in ___ that the process, acknowledges range expansion, and ignores __ even when it is the most likely explanation

Endemic

Cladistic vicariant biogeography is good if all taxa are __ in one are

Panbiogeography

Cladistic vicariant biogeography is now known as

Panbiogeography

contrary to dispersalist approach, it regards vicariance as the primary mechanisms for the distribution or organisms rather than dispersal

Vicariance

a biogeographic process where a continuous population or species range is split into isolated subpopulations by the formation of an extrinsic physical barrier, such as a mountain range, a new river, a glacier, or the rifting of tectonic plates.

Phylogeny (Dispersal-Vicariance Analysis), branch lengths, divergent time

• infers ancestral areas at nodes by minimizing the number of dispersal and extinction events using cost matrix

• favors vicariant approach to inferring biogeography, ignored ___and didn’t take __ into account

Model Based Biogeography, mechanistic models

infers biogeography using ____ of the biogeographical process with parameters representing dispersal, extinction, cladogenesis, etc.

Indomalayan/Australian Archipelago

Nawab butterflies are restricted to the

Polyura Billberg

Nawab butterfly genus

Eulepis Scudder, monophyletic, Charaxes

Polyura used to be under ___ and used to be considered ___ together with ___

Paraphyletic, Smiles, Polyura

Charaxes was established to be___ by ____and regards __ as its sister group

Morphological Traits, underwing patterns

• Drawbacks of Smile’s effort

• Phylogeny was described purely out of ___

• ____ was used to classify

38, monophyletic

• Using ____characters to construct a cladogram, Smiles proposed that Polyura as a ___ and can be separated from Charaxes

Reduced number of pattern elements, Charaxes-closed hindwing, Polyura-completely open

Basis of Charaxes and Polyura separation (2)

Polyura Scheiber

Polyura species in the Philippines

Synapomorphic Characters

a shared, evolutionarily derived character state found in two or more taxa and inherited from their most recent common ancestor. In biology, these traits act as crucial markers in cladistics to define clades and build phylogenetic trees

Molecular Species Delimitations

Use of multiple ____ on a multimarker dataset was proven efficient

Microevolution, observable changes

small scale changes in allele frequencies within a population over a relatively short period. This can lead to ___ in traits like color, size, or behavior within a species

Dispersal

One way movement of organisms or propagules from their birth site to a new breeding site

Mutation, new genetic variations

Random changes in the DNA sequence can introduce ___ into a population

Gene Flow

movement of individuals or gametes between populations can introduce new alleles into a population, altering its genetic composition

Genetic Drift, random fluctuations

---

in allele frequencies, especially in small populations can lead to loss or fixation of certain alleles resulting in significant changes in the genetic makeup of a population over time

Natural Selection

Individuals with advantageous traits are more likely to survive and reproduced, passing those traits on to their offspring

• migration, random event

• large, smaller

• inbreeding or interbreeding, sudden change

• through migration, bottleneck or founder effect

Gene Flow vs Genetic Drift

Macroevolution

large scale evolutionary changes that occur over long periods and result in the formation of new species. While it operates on a larger scale, the underlying mechanisms are the same

Speciation

process by which new species arise, often through geographic isolation or reproductive barriers

Adaptive Radiation

rapid diversification of a lineage into many new forms often filling ecological niches

Extinction

Disappearance of entire species or groups of species often due to environmental changes or competition

Convergent Evolution

independent evolution of similar traits in unrelated organisms often due to similar selective pressures

Mutation, Gene Flow, Geneti Drift, Natural Selection

Microevolution (4)

Speciation, Vicariance, Dispersal, Adaptive Radiation, Extinction, Convergent Evolution

Macroevolution (6)