New insights into the distribution of polyploid Daphnia: the Holarctic revisited and Argentina explored.

نویسندگان

  • Sarah J Adamowicz
  • T Ryan Gregory
  • María Cristina Marinone
  • Paul D N Hebert
چکیده

It has long been known that polyploid organisms are more prevalent in arctic than in temperate environments. Past explanations for this geographical trend have focused on the role of glacial cycles in generating polyploids and the influence of abiotic factors in favouring polyploidy in the north. In combination, these mechanisms probably suffice to explain the observed geographical cline in ploidy levels in members of the Daphnia pulex complex in the Holarctic. While only diploid members of the D. pulex complex are found in the temperate regions of North America and Europe, allozyme and DNA quantification analyses indicate that the southern Argentine pulex-complex fauna is dominated by polyploids. Indeed, the present study is the first to document the presence of polyploid members of the D. pulex complex in any temperate climate. The results of phylogeographic analyses suggest that this difference in polyploid distribution between the northern and southern hemispheres is based more on ecological and historical contingencies than direct selection for polyploidy. Specifically, competition with diploid relatives probably limits the lower latitudinal range of polyploids in the north, but appears not to have occurred in Argentina. Because of these differences, the present study provides important insights into the diverse factors that determine the distributions and evolutionary fates of polyploid organisms.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Induction of secondary axis in hydra revisited: New insights into pattern formation

In 1909, several years before the famous `Organizer’ experiments of Spemann and Mangold, Ethel Browne demonstrated induction of a secondary axis in hydra by grafting a hypostome. Based on this and subsequent work, in the late sixties, Lewis Wolpert proposed the theory of morphogen gradients and positional information. We have studied secondary axis induction by hypostome and foot tissue using t...

متن کامل

Quaternary diversification in a sexual Holarctic zooplankter, Daphnia galeata.

The effects of Quaternary glacial range partitioning on the diversification of Holarctic biota remain unclear. Glacial refugial lineages may form vicariant species, hybrid products, or merge after secondary contact. Here, we assess the effects of Quaternary glaciation on a Holarctic sexual zooplankter, Daphnia galeata, with apparently marked dispersal capacity and a widespread hybrid lineage in...

متن کامل

Polyploid Induction in Viola acuminata Ledebour using Colchicine

This study was aimed to obtain polyploid plants of viola (Viola acuminata Ledebour) using the antimitotic agent colchicine. Experiments consisted in using colchicine on ungerminated seeds. The seeds were plunged into colchicine solutions in concentrations of 0.01, 0.05, 0.10 and 0.20% for 24 and 48 h. Polyploidy levels (diploid, tetraploid and hexaploid) were firstly detected by chromo...

متن کامل

Effects of light and sound stimuli on spatial distribution and swimming activity of Daphnia under laboratory conditions

Aquatic ecosystems are heterogeneous in terms of light and sound distribution. The aim of this study was to investigate the effect of environmental abiotic factors, light and sound stimuli, on Daphnia (Daphnia magna) swimming behaviour.  Here, we examined behavioural changes of Daphnia (N=24) in response to light and sound treatments simultaneously. The treatments concerned a 2×2 design with br...

متن کامل

Bertrand’s Paradox Revisited: More Lessons about that Ambiguous Word, Random

The Bertrand paradox question is: “Consider a unit-radius circle for which the length of a side of an inscribed equilateral triangle equals 3 . Determine the probability that the length of a ‘random’ chord of a unit-radius circle has length greater than 3 .” Bertrand derived three different ‘correct’ answers, the correctness depending on interpretation of the word, random. Here we employ geomet...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Molecular ecology

دوره 11 7  شماره 

صفحات  -

تاریخ انتشار 2002