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Related Concept Videos

Statistical Hypothesis Testing01:16

Statistical Hypothesis Testing

Hypothesis testing is a critical statistical procedure facilitating informed, evidence-based decisions. It begins with a hypothesis, which is a tentative explanation, or a prediction about a population parameter. This hypothesis can be either a null hypothesis (H0), indicating no effect or difference, or an alternative hypothesis (Ha), suggesting an effect or difference.
Statistical significance measures the probability that an observed result occurred by chance. If this probability, known as...
Null and Alternative Hypotheses01:16

Null and Alternative Hypotheses

The actual hypothesis testing begins by considering two hypotheses. They are termed  the null hypothesis and the alternative hypothesis. These hypotheses contain opposing viewpoints.
The null hypothesis, denoted by H0 is a statement of no difference between the variables—they are not related. This can often be considered the status quo. As  a result if you cannot accept the null, it requires some action.
The alternative hypothesis, denoted by H1 or Ha, is a claim about the population that is...
Evolutionary Relationships through Genome Comparisons02:54

Evolutionary Relationships through Genome Comparisons

Genome comparison is one of the excellent ways to interpret the evolutionary relationships between organisms. The basic principle of genome comparison is that if two species share a common feature, it is likely encoded by the DNA sequence conserved between both species. The advent of genome sequencing technologies in the late 20th century enabled scientists to understand the concept of conservation of domains between species and helped them to deduce evolutionary relationships across diverse...
Hypothesis Test for Test of Independence01:16

Hypothesis Test for Test of Independence

The test of independence is a chi-square-based test used to determine whether two variables or factors are independent or dependent. This hypothesis test is used to examine the independence of the variables. One can construct two qualitative survey questions or experiments based on the variables in a contingency table. The goal is to see if the two variables are unrelated (independent) or related (dependent). The null and alternative hypotheses for this test are:
H0: The two variables (factors)...
Types of Hypothesis Testing01:11

Types of Hypothesis Testing

There are three types of hypothesis tests: right-tailed, left-tailed, and two-tailed.
When the null and alternative hypotheses are stated, it is observed that the null hypothesis is a neutral statement against which the alternative hypothesis is tested. The alternative hypothesis is a claim that instead has a certain direction. If the null hypothesis claims that p = 0.5, the alternative hypothesis would be an opposing statement to this and can be put either p > 0.5, p < 0.5, or p ≠ 0.5.
Test for Homogeneity01:23

Test for Homogeneity

The goodness–of–fit test can be used to decide whether a population fits a given distribution, but it will not suffice to decide whether two populations follow the same unknown distribution. A different test, called the test for homogeneity, can be used to conclude whether two populations have the same distribution. To calculate the test statistic for a test for homogeneity, follow the same procedure as with the test of independence. The hypotheses for the test for homogeneity can be stated as...

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HOX Loci Focused CRISPR/sgRNA Library Screening Identifying Critical CTCF Boundaries
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Published on: March 31, 2019

Statistical tests between competing hypotheses of Hox cluster evolution.

Robert Lanfear1, Lindell Bromham

  • 1Centre for the Study of Evolution, School of Life Sciences, University of Sussex, Brighton, UK. Rob.Lanfear@anu.edu.au

Systematic Biology
|October 15, 2008
PubMed
Summary

Hox and ParaHox gene evolution hypotheses were statistically compared. Five of eight models were rejected, suggesting the ancestral ProtoHox cluster had three or four genes.

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Area of Science:

  • Evolutionary developmental biology
  • Comparative genomics
  • Phylogenetics

Background:

  • Hox genes are crucial transcription factors for anterior-posterior patterning in bilaterians.
  • Gene duplication, particularly of Hox genes, is a key driver of animal body plan evolution.
  • Reconstructing the evolution of the Hox gene cluster is of significant research interest.

Purpose of the Study:

  • To statistically compare current hypotheses on Hox and ParaHox gene evolution.
  • To evaluate the validity of the widely assumed four-gene ProtoHox cluster duplication model.
  • To determine the most likely ancestral state of the ProtoHox cluster.

Main Methods:

  • Utilized two statistical methods to account for phylogenetic uncertainty.
  • Employed maximum-likelihood tree estimation and parametric bootstrapping for hypothesis comparison.
  • Applied Bayesian phylogenetics to assess posterior tree distributions and hypothesis support.

Main Results:

  • Statistical analyses provided congruent results.
  • Five out of eight considered hypotheses for Hox and ParaHox gene evolution were rejected.
  • Phylogenetic signal in homeodomains was insufficient to definitively distinguish between three- or four-gene ProtoHox clusters.

Conclusions:

  • The ancestral ProtoHox cluster likely contained either three or four genes.
  • The common hypothesis of a four-gene ProtoHox cluster duplication requires re-evaluation.
  • Further research may be needed to resolve the precise ancestral ProtoHox gene number.