DOI: 10.5061/dryad.gtht76hwz
title: Data from: Asexuality and species invasion

description: Founding populations of non-native species typically contain a small
 subset of their home range populations, exhibiting a reduced subset of
 their genetic diversity. Many of these non-native species predominantly,
 or even solely, engage in asexual reproduction, but it is unclear whether
 asexual reproduction is linked with species invasion. We used a systematic
 review of peer-reviewed literature to investigate whether species with
 reproductive polymorphisms are more often asexual in their invaded than
 native range. We also investigated whether genetic diversity was higher in
 home than invaded ranges. We found 219 relevant studies, and those showed
 that asexual reproduction is three times more common in invaded than home
 ranges, and higher genetic diversity is 20 times more common in home than
 invaded ranges for these organisms (this difference highest in the more
 recently introduced species). Hence, asexual reproduction appears
 associated with species invasion. Whereas asexual reproduction lacks the
 genetic mixing needed to respond to heterogenous environments and natural
 enemies, it confers several advantages for small founding populations,
 including the ability to establish new populations from a single or very
 few founding members with no requirement for finding a mating partner or
 pollinator, and asexual species invasion often brings relatively low
 intraspecific competition (allowing monoculture domination). For
 non-native species, high phenotypic plasticity and a lack of natural
 enemies may offset the disadvantages of asexual reproduction, leading to
 enhanced success for asexual non-native plants and animals.
description: We followed the recommendations for reporting items for
 systematic review as outlined by Moher et al. (2009). We generated a list
 of peer-reviewed journal articles that reported results for asexual
 reproduction in non-native species using the search terms “non-native” or
 “invasive” with “asexual”, “apomixis,” “cleistogamy,”
 “self-fertilization,” “clone” or “parthenogenesis” in September-December
 2020. We did not place date or language restrictions. We used the default
 search engine settings for the Science Citation Index Expanded
 (1970-present) but excluded the Social Sciences and Arts &
 Humanities citation indices. We also refined the search by “article.” We
 removed 70 results that were replicates between search terms. The search
 produced a master list of 409 articles. Graduate students (at least two
 students per article) examined each journal article and screened out
 reviews, meta-analyses, simulations, non-English papers, and papers with
 multiple species, leaving 132 papers for analysis. We note that, beyond
 initial training, the graduate students assessed the applicability of the
 reviewed articles independent of the authors of this review. We also note
 that more recent treatments often separate “non-native” and “invasive”
 descriptors but, as this review spans the transition in terminology, we
 included both terms as search items.  
 Given that a search directed toward asexual reproduction in
 non-native species risked overestimating asexuality in non-native species,
 we attempted to ameliorate this prejudice by using an independent
 compendium of species that focused on non-native status only, and then we
 investigated sexual polymorphism in all species on that list. We used the
 species list from the “100 of the worst invasive species” list (Lowe et
 al. 2004), which generated 98 additional records (we excluded two
 viruses). There were 13 species in common between the first “asexual” and
 second “worst” searches, leaving a total of 219 species records in the
 merged data set<sup></sup>.
   We categorized each species as fish,
 invertebrate, mammal, pathogen, plant, or ‘other.’ Fungi, herpetofauna,
 and birds were placed in the ‘other’ category as each was found in
 &lt; 5 papers (<em>n</em> = 11 total), which was
 considered too few for meaningful interpretation. We also used these data
 to further investigate the literature for differences in genetic diversity
 between home and invaded ranges and whether the species was reported as
 being polyploid, but we did not assess the individual metrics of genetic
 diversity used in each paper – which might add error as the method of
 assessment could result in different predictions.
description: # Data from: Asexuality and species invasion **File name: Data.csv**
 Variables: Ident = identifying line Confidence = weighted confidence level
 (0 = not appropriate for the review; 1 = requires some inference to meet
 review objectives; 2 = mostly meets review objectives and 3 = meets review
 objectives) Common = common name Scientific = scientific name First.report
 = first reported as an invader Type = type of organism (Plant,
 invertebrate, fish, mammal, pathogen, other) Invaded.rage = invaded range
 Origin.range = range of origin Origin = data for home or invaded range
 populations Reproduction = mode (asexual, sexual, both) Higher.genetic =
 in which population (home or invaded) is genetic diversity higher (1,0)
 Polyploid = are they reported as polyploid? Data.set = systematic review,
 100 worst invaders or both Missing data: NA