STEB: Advanced

Advanced

In this category, those who have entered the STEB competition just once are competing. The individual series can be found here.

Series 1: Studying genomics of natural populations

Genes are an extremely important tool for evolutionary biologists and many other scientists: they can be used to understand how species are similar or how they differ, as well as to reveal relationships that may not be obvious from physical appearances. In this article, we will join Dasha, a young scientist and the author of this article, on a research project she conducted to better understand an unusual population of birds in the Ural Mountains. These birds closely resembled two different bird species -- they shared some physical characteristics with each, and even sang the songs of both species! We'll learn how Dasha used genes to unravel the mystery surrounding these birds, and about her journey to collect the genetic data and analyze it. Along the way we will see how modern genetic approaches can answer evolutionary questions and witness the journey of a DNA sample from the sampling site to the computer screen.


Author: Daria Shipilina

Series 2: The secret world of plant sex

How do plants choose a mate? Unlike animals, plants can't get up and move around to find a potential mating partner. In most plant species, each plant has male and female reproductive organs. Some plants ensure they have a mate by pollinating themselves (self-pollination). Yet, many plants do not self-pollinate but mate with another plant of the same species (``outcrossing''). These plants need to make use of wind or water to move their pollen or convince animals such as bees to carry their pollen to another plant. When pollen arrives they need to solve another problem: is this mine or another plant's pollen? In this issue, you will learn why so many plant species are outcrossing and get to know some ingenious incompatibility systems they use to avoid self-pollination.


Authors: Katarína Boďová and Melinda Pickup

Series 3: Viruses in the world of bacteria

When you think of viruses, you probably think of diseases that affect you and other people: influenza, measles, rubella and many more. However, humans are not the only victims of viruses. In fact, the first virus ever discovered did not cause a disease in humans but in tobacco plants. Today, we know that viruses are ubiquitous and infect all forms of life -- humans, birds, plants, insects, etc. There is no living species that is not affected by viruses; not even bacteria are safe from them! Some viruses kill bacteria, others bring benefits to their bacterial hosts. Let's take a closer look at this miniature world of attack and defense!


Authors: Hildegard Uecker and Barbora Trubenová

Series 4: Origin of Eukaryotes

All living organisms are composed of one or more cells, and all cells can be classified as either prokaryotic or eukaryotic. For more than half of the history of life on Earth (about two billion years), the Earth was inhabited by simple, single-celled organisms similar to today's bacteria, known as prokaryotes.

Though there are still millions of prokaryotes in any given environment, including on and within the human body, the organisms we are most familiar with - animals, plants, and fungi - are composed of cells of the other type, eukaryotic cells.


Author: Kristína Hudáková

Series 5: Branches in the tree of life: how new species evolve

Many of us have been awestruck by the amazing diversity of life forms all around us. Scientists estimate that the number of species on our planet may be anywhere from a few million to a whopping one trillion. (The huge uncertainty in this estimate is largely due to the difficulties in counting bacterial species). But what exactly are species, and how do they evolve?


Author: Himani Sachdeva