The curse of the mother of mankind
Raivo Mänd looks at conflicts of gender interests that go with gender and sexuality. With a gentle touch of humor, the author describes the different strategies of breeding in the rich animal world. With a little bit of exaggeration we can view the spermatozoids as parasites, which spread their genes in the female egg, taking effective advantage of the resources found in the egg. For most animals it is common that males have the urge to spread as many spermatozoids as possible, while females are far more picky and do not fall for every interested male.
Sexual reproduction remains a mystery for evolutionists
Toomas Tammaru states that sexual reproduction is costly and the benefits are questionable. He points out that it is very much possible to reproduce successfully also in the unsexual way. Although sexual reproduction is costly, there are several benefits of that – for example, those life forms that breed sexually possess a bigger evolutionary potential. According to another theory, sexual breeding is good for avoiding parasites, which might become too used to parent individuals of the same genotype. However, it is likely that the benefits of sexual reproduction are determined by a complex of different mechanisms and one, clear explanation for that does not exist.
When did the gender features appear in the animal world?
Ivar Puura and Oive Puura recall the old times when male and female sexes just started to develop in the animal world. Most probably different sexes were already dominant among the Metazoa that developed in early Cambrium. The oldest fossils for which we can differentiate between males and females are ostracodes – species of Palaeocopida that are about 480 million years old. These are also found in the Ordovician limestones of Estonia.
Edgar Kask’s meditation on bird’s cherry and picket fence
Invertebrates breed like in an action movie
Mati Martin takes the reader to the diverse and exciting world of invertebrate breeding. Most of the invertebrates have two sexes. There are innumerous ways of reproduction, starting from those, whose partners never actually meet each other, to those, whose males sponge upon the females. Sometimes the act of copulation is dangerous for one of the partners, such as for the males of spiders, who have to do tricks to get anywhere near the female alive.
Through the forests of Northern Kõrvemaa
Tiina Neljandik continues the journey through Lahemaa and Kõrvemaa – this time in the forests and bogs, lakes and eskers of Kõrvemaa. The landscapes of Northern Kõrvemaa usually offer a surprise for the newcomers – the varied relief with all kinds of eskers, kames, end moraines and other hills form a real open-air museum of postglacial landforms. The numerous picturesque lakes add to the spirit of the area.
Eesti Loodus asks
Ahto Kaasik tells about the plan to review the holy groves of Estonia.
Annelie Ehlvest introduces ways to get acquainted with the nature protection objects of Tartu.
What is the gender of a plant without gender chromosomes?
Ülle Reier gives an overview of the present knowledge of determining and expression of plant genders. First gender chromosomes of plants were discovered about a hundred years ago on plants of dioecy. However, no gender chromosomes have yet been detected for many of these plants. Environmental conditions can also be extremely important for the development of genders. For some plants the gender depends on vegetation period: first year flowers are male, but the second year flowers female.
Interview: animals of zoos breed just like in reality
Toomas Kukk has interviewed Aleksei Turovski, a zoologist and biosemiotist.
Prangli landsape protection area
Uudo Timm introduces the unique and very vulnerable nature of two islands in the Gulf of Finland – islands of Prangli and Väike-Prangli, or Aksi.
The land of the long white cloud
Valdo Kuusemets describes the variegated and diverse fauna and flora of New Zealand. The nature of this faraway place is extraordinary, because of its isolation from other continents, its large territory and varied conditions. It is like a unique natural museum, but at the same time a warning against unthoughtful activities of man.
”Euro” waste sites: bless or misery?
Kert Saar discusses the necessity of Euro-standard waste sites: does the creation of such sites increase or decrease the environmental pollution?