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27 Aug 2018

One theory of human evolution suggests that Homo erectus evolved directly into Homo sapiens (humans), after which point Homo erectus became extinct. If this is true, humans arose by ________.

allopatric speciation

cladogenesis

anagenesis

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14 Jun 2023

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Related questions

. Take a look at the skull of Homo floresiensis (nicknamed “the Hobbit”). This is a very small hominin species that lived on the island of Flores in Indonesia at the same time as modern humans were living elsewhere in Southeast Asia, including other parts of Indonesia. There is some controversy among paleoanthropologists concerning whether this hominin should actually be considered a member of Homo sapiens, rather than its own species. Some people believe that this skull, and others that have been found on the island, simply came from a modern human (Homo sapiens) with a very small head, such as we see in people with a condition known as microcephaly. Assume that this is actually the correct interpretation - that “the Hobbits” were a small, isolated population of modern humans that evolved to have very small brains and skulls following their divergence from a mainland Indonesian human population. If this is the case, which evolutionary mechanism(s) might have produced this dramatic change in skull anatomy? Explain your answer.

1. According to scientists who accept the （______) model, gene flow and migration between populations of archaic humans from different regions led to one species over time (i.e. modern humans).

2.

Both the replacement and multiregional models of human origins agree that there was an initial dispersal of Homo erectus (or ergaster) from (_______) into the rest of the Old World.

3.

According to the ecological species concept, in some cases different species:

A. can never produce offspring
B. can breed and produce offspring under unnatural circumstances
C. can only produce offspring in they live in the same ecosystem

4.

Punctuated equilibrium and Gradualism are models that explain:

A. Darwin's ideas about evolutionary change
B. small evolutionary changes over time
C. the rate at which evolution occurs over time
D. the kinds of species that are most likely to change via the evolutionary process

5.

Which of the following best describes punctuated equilibrium?

A. the rate of evolutionary change is always slow and gradual
B. the relatively rapid expansion and diversification of life forms into new ecological niches
C. evolution occurs slowly most of the time, with occasional bursts of relatively rapid periods of change
D. the evolution of a new species
E. evolutionary change based on the differential reproductive success of an individual in a species

16. Which of the following is not an example of allopatric speciation?

A) The Isthmus of Panama arose 10 million years ago dividing a species of snapping shrimp into two separate populations. Over time, individuals on one side of the isthmus became reproductively isolated from individuals on the other side.

B) A species of hummingbird lives on mainland Costa Rica. Ten individuals make their way to a small island off the coast. Over time these island birds become reproductively isolated from the mainland birds.

C) A squirrel population was divided into two groups because of the formation of the Grand Canyon. Since that time, genetic changes have occurred and the two groups of squirrels are now reproductively isolated from one another.

D) Two populations of deer are separated by a river. Over millions of years, the river dries up. When the two deer populations meet, they are able to interbreed successfully.

E) All of these are examples of allopatric speciation.

Why is D considered allopatric speciation? I thought that D is the correct answer because if the two deer populations are able to interbreed, then speciation did not occur; so it cannot be considered allopatric speciation. ​

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