How does cross-fertilisation increase genetic variability?

Cross-fertilisation increases genetic variability by combining genetic material from two different individuals, creating unique offspring.

Cross-fertilisation, also known as outcrossing, is a fundamental process in sexual reproduction where the genetic material from two different individuals is combined to produce offspring. This process is crucial in increasing genetic variability, which is the diversity of alleles within a population. Genetic variability is a key factor in evolution and adaptation as it provides the raw material for natural selection to act upon.

In cross-fertilisation, the offspring inherit a mix of traits from both parents. This is due to the process of meiosis, where the number of chromosomes is halved in the sex cells, or gametes, and then combined during fertilisation. Each gamete carries a different set of genetic information, so when they combine, the resulting offspring has a unique set of genes. This is different from self-fertilisation, where the offspring are genetically identical to the parent.

Moreover, during meiosis, a process called crossing over occurs. This is where homologous chromosomes exchange genetic material, creating new combinations of genes. This further increases the genetic variability in the offspring.

Another important aspect of cross-fertilisation is that it allows for the masking of deleterious recessive alleles. If an individual carries a harmful recessive allele, it can be masked by a dominant allele from the other parent. This can increase the fitness of the offspring and the overall population.

In addition, cross-fertilisation can lead to greater adaptability in changing environments. With a wider range of genetic variation, there is a higher chance that some individuals in the population will possess traits that allow them to survive and reproduce under new conditions. This can lead to the evolution of new species over time.

In conclusion, cross-fertilisation plays a crucial role in increasing genetic variability. It allows for the combination of different genetic material, the creation of new gene combinations, the masking of harmful alleles, and greater adaptability to changing environments.