Models for the generation and interpretation of spatial patterns are discussed. Crucial for these processes is an intimate link between self-enhancing and antagonistic reactions. For spatial patterning, long-ranging antagonistic reactions are required that restrict the self-enhancing reactions to generate organizing regions. Self-enhancement is also required for a permanent switch-like activati...

Hybrid Phoxinus are one of the few asexually reproducing vertebrates species. The distribution of hybrid Phoxinus among lakes in Algonquin Park, Ontario, was evaluated relative to the distribution of parental species and relative to physiochemical lake characteristics. No association between the distribution of hybrids and the distribution of parental species was found, suggesting that the hybr...

Using a bit string model, we show that asexual reproduction for diploids is more efficient than for haploids: it improves genetic material producing new individuals with less deleterious mutations. We also see that in a system where competition is present, diploids dominate, even though we consider some dominant loci.

U nderstanding the emergence of sexual reproduction has been one of nature’s long-standing mysteries that even now is only partially understood. There is a clear distinction between the reason sex evolved in the first place in early eukaryotes—and even before that in prokaryotes—and why it has been so stubbornly maintained in virtually all higher species. After all, asexual reproduction is supe...

The mode of reproduction has been predicted to affect the proliferation of transposable elements (TEs). A population that switches from sexual to asexual reproduction could either accumulate TEs because purifying selection becomes less efficient, or a decrease in TE load because the opportunity for horizontal transmission is reduced. A third possibility is that the mechanism that induces asexua...

Traditionally, regeneration research has been closely tied to flatworm research, as flatworms (Plathelminthes) were among the first animals where the phenomenon of regeneration was discovered. Since then, the main focus of flatworm regeneration research was on triclads, for which various phenomena were observed and a number of theories developed. However, free-living flatworms encompass a numbe...

Different types of sediments in salt marsh have different physical and chemical characters. Thus sediment type plays a role in plant competition and growth in salt marsh ecosystems. Spartina anglica populations have been increasingly confined to upper elevation gradients of clay, and the niche sediment has changed. Because the niches of S. anglica and the native species Scirpus triqueter overla...

Patterns of reproductive uncertainty can have an important influence on population dynamics. There is a crucial distinction between what we describe here as aggregate uncertainty (in which reproductive output in each generation is correlated among the individuals in a population) and idiosyncratic risk (in which reproductive output is independent across individuals). All else being equal, popul...

For many decades, polymorphism and its consequences have only been studied from the taxonomic point of view. Presently, interest has switched to the environmental causes of morphological variation and its consequences in the form and essence of the species. This study aimed at evaluating desmids morphological modifications of Staurastrum rotula Nordstedt during inter-annual succession patterns ...