Radu GuiasuYork University · Biology Program, Glendon College (Glendon campus of York University)
Radu Guiasu
PhD, University of Toronto
About
79
Publications
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Introduction
I am a biologist and a tenured professor in the Biology Program at Glendon College, York University in Toronto, Canada. My main areas of interest and expertise are non-native species (animals and plants), invasion biology (an alternative, critical look at aspects of invasion biology), ecology, ethology, biogeography, conservation biology, biodiversity (especially new measures of biodiversity), systematics, cladistics, freshwater ecosystems, astacology (crayfish), and ichthyology (fish).
Education
October 1991 - February 1997
October 1988 - July 1989
October 1986 - February 1991
Publications
Publications (79)
The young field of invasion biology - initially a branch of ecology and conservation biology - has greatly expanded, particularly in the last two and a half decades or so. As a result, the potential negative effects of introduced species have been widely advertised and sometimes, perhaps, overemphasized. This book attempts to restore some balance t...
The crayfish genus Fallicambarus Hobbs, 1969 contains 16 species. All of these are semi-terrestrial burrowers found in the eastern half of North America. A total of 75% of the Fallicambarus species is currently endangered, threatened, or vulnerable, and these therefore, require special attention from a conservation standpoint. The most widely distr...
Optimization of yellow juvenile coloration on a previously published genus-level cladogram of acanthurid fishes predicts that such coloration is either plesiomorphic (given that the species with yellow juveniles are basal in their respective genera, 6 steps minimum), or that this coloration has developed independently (4 steps minimum). These hypot...
The distribution of biodiversity at multiple sites of a region has been traditionally investigated through the additive partitioning of the regional biodiversity into the average within-site biodiversity and the biodiversity among sites. The standard additive partitioning of diversity requires the use of a measure of diversity, which is a concave f...
During agonistic contests between size-matched Cambarus robustus crayfish males of breeding form, the eventual winners and losers initiated approximately the same number of fights. However, winners and losers differed in the frequencies and types of initiation behaviours used. The losers used almost exclusively the more subtle Ambivalent Contact in...
Freshwater crayfish are amongst the largest macroinvertebrates and play a keystone role in the ecosystems they occupy. Understanding the global distribution of these animals is often hindered due to a paucity of distributional data. Additionally, non-native crayfish introductions are becoming more frequent, which can cause severe environmental and...
Records count per crayfish taxa integrated in WoC platform.
Crayfish and A. astaci records integrated in WoC platform count per major hydrographic basins.
Crayfish and A. astaci records integrated in WoC platform count per country.
This is an autobiographical novel about growing up under the rule of a communist dictatorship in Romania decades ago. It is an often hilarious and sometimes heartbreaking exploration of the absurdities of life under an increasingly erratic dictatorship which was gradually losing its grip on the people it could never fully control.
We analyze the “Logical fallacies and reasonable debates in invasion biology: a response to Guiaşu and Tindale” article by Frank et al., and also discuss this work in the context of recent intense debates in invasion biology, and reactions by leading invasion biologists to critics of aspects of their field. While we acknowledge the attempt by Frank...
Human-made facilities and major construction projects, like navigation canals and water-transfer canals and pipelines, can facilitate the spread of aquatic alien species, some of which may have negative impacts on the habitats invaded, and on the economy. However, the positive economic impacts of such facilities are usually much higher than their c...
The economic costs of non-indigenous species (NIS) are a key factor for the allocation of efforts and resources to eradicate or control baneful invasions. Their assessments are challenging, but most suffer from major flaws. Among the most important are the following: (1) the inclusion of actual damage costs together with various ancillary expenditu...
The distribution of the semi-terrestrial burrowing crayfish Creaserinus fodiens (Cottle, 1863) in Ontario was updated based on the examination of records stored in the crayfish database of the Royal Ontario Museum in Toronto and specimens collected during field studies. New Ontario locality records are reported for this crayfish from MacGregor Poin...
Although isolated records of nonindigenous species (i.e., species transported with the aid of human activities outside of their native geographic ranges) have been known for centuries, the first comprehensive work on these organisms and their impacts is the book by Charles Elton published in 1958. The rate of species introductions increased signifi...
The concept of native range in invasion biology is difficult to define since, in many cases, this type of range is unknown and cannot be determined. We investigate the uncertainties related to this concept by focusing on the distribution of Faxonius rusticus (Girard, 1852), also known as the rusty crayfish, which is perceived as possibly the worst...
Leading invasion biologists sometimes dismiss critics and criticisms of their field by invoking “the straw man” fallacy. Critics of invasion biology are also labelled as a small group of “naysayers” or “contrarians”, who are sometimes engaging in “science denialism”. Such unfortunate labels can be seen as a way to possibly suppress legitimate debat...
The common carp (Cyprinus carpio) is listed as one of the world's worst invasive species and expensive control programs are undertaken against this freshwater fish in various regions where it was introduced, including North America. A thorough review of the relevant scientific literature has revealed that at least some of the anti-common carp infor...
Orconectes rusticus is considered to be invasive in many parts of North America, including Ontario, and is the target of control programs. However, the limits of the native range of this species, as well as its means and rate of dispersal are uncertain, and it is quite possible that this crayfish may in fact be native to parts of the continent wher...
Purple loosestrife (Lythrum salicaria) is listed as one of the world's worst invasive species by the World Conservation Union (IUCN). Expensive control programs are undertaken against this wetland plant in North America, including the Great Lakes region. A thorough review of the relevant scientific literature has revealed that the anti-purple loose...
Orconectes rusticus is the most reviled crayfish in North America, because this species is considered to be invasive in many parts of this continent. We examine the available information about this species, particularly in Ontario, and we argue that caution should be exercised when implementing control programs against this crayfish, given that the...
Preparation of an Integrated Management Plan for the Pafos Forest. Republic of Cyprus – Ministry of Agriculture, Natural Resources and Environment – Department of Forests.
The distribution of biodiversity at multiple sites of a region has been traditionally investigated through the additive partitioning of the regional biodiversity, called γ-diversity, into the average within-site biodiversity or α-diversity, and the biodiversity among sites, or β-diversity. The standard additive partitioning of diversity re-quires t...
Both the weighted entropy, which generalizes the Shannon entropy, and the weighted quadratic index, which generalizes the Gini-Simpson index, are used for getting a unified treatment of some diversity measures proposed recently in ecology. The weights may reflect the ecological importance, rarity, or economic value of the species from a given habit...
In a numerical entity-characteristic incidence ma-trix we can use simple or multiple regression and calculate correlations between pairs of char-acteristics. However, in order to detect similari-ties/dissimilarities, interdependence, and multiple probabilistic causality among the characteristics we have to group the entities in classes. The num-ber...
The Gini-Simpson quadratic index is a classic measure of diversity, widely used by ecologists. As shown recently, however, this index is not suitable for the measurement of beta diversity when the number of species is very large. The objective of this paper is to introduce the Rich-Gini-Simpson quadratic index which preserves all the qualities of t...
The crayfish genus Cambarus Erichson, 1846 contains 97 species found in a wide diversity of freshwater aquatic and semi-aquatic habitats in eastern and central regions of North America. The greatest diversity of this genus is found in the south-eastern areas of the United States, particularly in states such as Tennessee, Georgia, North Carolina, an...
An exploration of the vague concept of ”native range” with examples from the distributions of North American crayfish species.
The article focuses on non-native and invasive species and some of the claims made about such species. This article was published in ROM - The Magazine of the Royal Ontario Museum 40 (4): 26-33 (Spring 2008 issue).
This is a summary of the conservation status and possible threats to Ontario crayfish species, such as the river and lake species Cambarus bartonii and Cambarus robustus, and the semi-terrestrial species Fallicambarus fodiens.
Informal observation suggested that Fallicambarus fodiens, which lives in close aggregations of mud burrows, exhibits less aggression than related epigean Cambarus spp. Interactions between size-matched, same sex pairs of F. fodiens were analysed in the laboratory. The analysis shows that these crayfish use behaviours similar to those used by Camba...
This book is the result of a collaboration between a biologist and a mathematician. The book deals with the entropic measures of uncertainty, diversity, and interdependence and the applications of these measures to the fields of ecology and ethology.
Shannon's entropy and Simpson's index are the most used measures of species diversity. As the Simpson index proves to be just an approximation of the Shannon entropy, conditional Simpson indices of diversity and a global measure of interdependence among species are introduced, similar to those used in the corresponding entropic formalism from infor...
This book is the result of a collaboration between a biologist and a mathematician. The book deals with the entropic measures of uncertainty, diversity, and interdependence, and the applications of these measures to the fields of ecology and ethology.
This is an article about the conservation of burrowing, semi-terrestrial crayfish in Ontario, Canada. The article was published in Rotunda - The Royal Ontario Museum Magazine 35 (1): 22-27 (Summer/Fall 2002 issue).
Cambarus robustus crayfish kept and monitored under constant summer-like photoperiod and temperature conditions in the laboratory did not moult during the winter months. The timing of the moulting events in the laboratory closely matched the timing of the corresponding types of moults in the field for adult Form I and Form II males, adult females,...
The vast majority of tested juvenile crayfish of Fallicambarus fodiens consistently preferred conspecific-built mud chimneys over similar-looking human-built chimneys. When the chimneys were surrounded by transparent acetate sheets, the crayfish no longer discriminated between conspecific-built and human-built chimneys. This suggests that visual cu...
During contests between evenly size-matched Cambarus bartonii bartonii crayfish males of reproductive form (Form I), the eventual winners performed significantly more total initiation acts, Lunge and Claws Raised initiation behaviours than the eventual losers. There were no significant differences between the numbers of Ambivalent Contact initiatio...
The two closely related, surface water crayfish species, Cambarus bartonii bartonii and Cambarus robustus, have similar habitat requirements and similar, asynchronous life cycles, but largely non-overlapping distributions in Ontario, Canada. Five types of agonistic contests (interspecific and intraspecific in each species) between evenly size-match...
ABSTRACT In the Province of Ontario, Canada, the two closely related crayfish species, Cambarus bartonii bartonii and Cambarus robustus, appear to have similar habitat requirements and similar, asynchronous life cycles, but largely nonoverlapping distributions. The analysis of the interspecific agonistic contests between size-matched males of these...
In this study, we evaluate the aggressive interactions between breeding form (Form I) and non-breeding form (Form II) male crayfishes, Cambarus robustus, during inter-form contests, and compare these data to those from previous studies on intra-form contests in this species. The analysis of inter-form agonistic contests between size-matched crayfis...
Several mean deviations from independence, including Pearson’s chi-square indicator and Kullback-Leibler’s divergence, are compared in the context of classification theory. An application to an example from the study of animal behaviour is presented. The construction of the joint distribution by minimizing the mean deviation from independence subje...
An analysis of intra-form agonistic contests between size-matched male Form II (non-breeding form) Cambarus robustus Girard, 1852 crayfish revealed that the winners and losers of these contests differed in the numbers and types of initiation behaviours used. The (eventual) winners, which initiated significantly more fights overall, used mostly the...
During agonistic contests between size-matched Cambarus robustus crayfish males of breeding form, the eventual winners and losers initiated approximately the same number of fights. However, winners and losers differed in the frequencies and types of initiation behaviours used. The losers used almost exclusively the more subtle Ambivalent Contact in...
This comprehensive update of the distribution of crayfishes of the genera Cambarus and Fallicambarus in Ontario includes substantial material collected since 1965 and a reexamination of previous records. Revised provincial range limits are presented for two wide-ranging, openwater species, C. bartonii bartonii and C. robustus, as well as for 2 obli...
A study of the osteology of the Acanthuridae (surgeonfishes) and a cladistic analysis of the 42 osteological and external characters resulted in a well-corroborated hypothesis (consistency index = 0.96) of the phylogenetic relationship of the six recognized acanthurid genera. Removal of autapomorphies for terminal taxa resulted in a data matrix of...
University Microfilms order no. UMI00294414. Thesis (M. Sc.)--University of Toronto, 1991. Includes bibliographical references.
Questions
Question (1)
I am working on the changing distributions of several crayfish species, and I need to be able to generate both local maps (of the Greater Toronto Area and Southern Ontario, for example) as well as more general maps (of all of Ontario, Canada, and North America). The local maps should include detailed features such as river systems, and I should be able to input data and plot include various locations where the species are found, of course, as distribution dots on the maps. I am interested in your suggestions about which types of map-generating software would be best overall (in terms of quality of results, ease of use, affordability, availability, and so on). Thank you.