A phylogenetic perspective of chromosome evolution in Formicidae.

Chromosomes, as carriers of genes, are the fundamental units of heredity, with the eukaryotic genome divided into multiple chromosomes. Each species typically has a consistent number of chromosomes within its lineage. Ants, however, display remarkable diversity in chromosome numbers, and previous studies have shown that this variation may correlate with ant diversity.

Shifts in Chromosome Evolution Rates Shape the Karyotype Patterns of Leafcutting Ants.

Trait evolution has become a central focus in evolutionary biology, with phylogenetic comparative methods offering a framework to study how and why traits vary among species. Identifying variations in trait evolution rates within phylogenies is important for uncovering the mechanisms behind these differences. Karyotype variation, which is substantial across eukaryotic organisms, plays an essential role in species diversification.

De novo assembly of the complete mitochondrial genome of Mycetophylax simplex Emery, 1888 through organelle targeting revels no substantial expansion of gene spacers, but rather some slightly shorter genes.

Mitochondria play a key role in cell biology and have their own genome, residing in a highly oxidative environment that induces faster changes than the nuclear genome. Because of this, mitochondrial markers have been exploited to reconstruct phylogenetic and phylogeographic relationships in studies of adaptation and molecular evolution. In this study, we determined the complete mitogenome of the fungus-farming ant Mycetophylax simplex (Hymenoptera, Formicidae) and conducted a comparative analysis among 29 myrmicine ant mitogenomes.

Assessing ploidy levels and karyotype structure of the fire ant Smith, 1855 (Hymenoptera, Formicidae, Myrmicinae).

The family Formicidae is composed of ants that organize themselves into castes in which every individual has a joint organizational function. Westwood, 1840 is an ant genus with opportunistic and aggressive characteristics, known for being invasive species and stings that cause burning in humans. This genus is particularly difficult to classify and identify since its morphology provides few indications for species differentiation.

Dynamic development of AT-rich heterochromatin has followed diversification and genome expansion of psammophilous Mycetophylax (Formicidae: Attini: Attina).

Heterochromatin is an important genome constituent comprised by a high density of repetitive DNA sequences that mediate chromosome structure and function. The species Mycetophylax morschi currently harbours three cytotypes: 2n = 26, 2n = 28 and 2n = 30 chromosomes. However, Mycetophylax conformis and Mycetophylax simplex harbour 2n = 30 and 2n = 36 chromosomes, respectively.

Karyotype Diversity, Mode, and Tempo of the Chromosomal Evolution of Attina (Formicidae: Myrmicinae: Attini): Is There an Upper Limit to Chromosome Number?

Ants are an important insect group that exhibits considerable diversity in chromosome numbers. Some species show only one chromosome, as in the males of the Australian bulldog ant , while some have as many as 60 chromosomes, as in the males of the giant Neotropical ant . Fungus-growing ants are a diverse group in the Neotropical ant fauna, engaged in a symbiotic relationship with a basidiomycete fungus, and are widely distributed from Nearctic to Neotropical regions.

Karyotype structure and cytogenetic markers of and : contribution to understanding leaf-cutting ant relationships.

Leaf-cutting ants are considered the most important herbivores in terrestrial environments throughout the Neotropics. Cristiano, Cardoso, & Sandoval, 2020 is the sister clade of the remaining leaf-cutting ants from the genera and . was the only species cytogenetically studied within the genus and shares the same chromosomal number as , bearing 22 chromosomes, whereas bears 38 chromosomes, with the exception of the social parasite (2 = 36).

Comparative FISH-mapping of TTAGG telomeric sequences to the chromosomes of leafcutter ants (Formicidae, Myrmicinae): is the insect canonical sequence conserved?

Telomeric sequences are conserved across species. The most common sequence reported among insects is (TTAGG), but its universal occurrence is not a consensus because other canonical motifs have been reported. In the present study, we used fluorescence hybridization (FISH) using telomeric probes with (TTAGG) repeats to describe the telomere composition of leafcutter ants.

Intraspecific variation in the karyotype length and genome size of fungus-farming ants (genus Mycetophylax), with remarks on procedures for the estimation of genome size in the Formicidae by flow cytometry.

Ants (Formicidae) present considerable diversity in chromosome numbers, which vary from n = 1 to n = 60, although this variation is not proportional to that in genome size, for which estimates range from 0.18 pg to 0.77 pg.

Karyotype and putative chromosomal inversion suggested by integration of cytogenetic and molecular data of the fungus-farming ant Emery, 1888.

Comparative cytogenetic analyses are being increasingly used to collect information on species evolution, for example, diversification of closely related lineages and identification of morphologically indistinguishable species or lineages. Here, we have described the karyotype of the fungus-farming ant Emery, 1888 and investigated its evolutionary relationships on the basis of molecular and cytogenetic data. The karyotype consists of 2n = 20 chromosomes (2K = 18M + 2SM).

Thermal Tolerance of Fruit-Feeding Butterflies (Lepidoptera: Nymphalidae) in Contrasting Mountaintop Environments.

Ectothermic organisms, such as insects, are highly temperature dependent and are good models for studies that predict organisms' responses to global climate change. Predicting how climate change may affect species distributions is a complicated task. However, it is possible to estimate species' physiological constraints through maximum critical temperature, which may indicate if the species can tolerate new climates.

Daily Dynamics of an Ant Community in a Mountaintop Ecosystem.

Abiotic conditions have a great influence on the structure of biological communities, especially considering ectothermic organisms, such as ants. In this study, we tested whether the daily temporal dynamics of an ant community in a tropical mountainous ecosystem is driven by daily fluctuations of abiotic factors, such as temperature and humidity. We also investigated whether the strong oscillation in daily temperature leads to high heterogeneity in ant species thermal responses.

Chromosomal dynamics in space and time: evolutionary history of Mycetophylax ants across past climatic changes in the Brazilian Atlantic coast.

Fungus-farming ants of the genus Mycetophylax exhibit intra and interspecific chromosome variability, which makes them suitable for testing hypotheses about possible chromosomal rearrangements that endure lineage diversification. We combined cytogenetic and molecular data from Mycetophylax populations from coastal environments to trace the evolutionary history of the clade in light of chromosomal changes under a historical and geographic context. Our cytogenetic analyses revealed chromosomal differences within and among species.

The evolution of haploid chromosome numbers in Meliponini.

It is thought that two evolutionary mechanisms gave rise to chromosomal variation in bees: the first one points to polyploidy as the main cause of chromosomal evolution, while the second, Minimum Interaction Theory (MIT), is more frequently used to explain chromosomal changes in Meliponini and suggests that centric fission is responsible for variations in karyotype. However, differences in chromosome number between Meliponini and its sister taxa and in the karyotype patterns of the Melipona genus cannot be explained by MIT, suggesting that other events were involved in chromosomal evolution. Thus, we assembled cytogenetical and molecular information to reconstruct an ancestral chromosome number for Meliponini and its sister group, Bombini, and propose a hypothesis to explain the evolutionary pathways underpinning chromosomal changes in Meliponini.

Chromosomal variation among populations of a fungus-farming ant: implications for karyotype evolution and potential restriction to gene flow.

Background: Intraspecific variation in chromosome structure may cause genetic incompatibilities and thus provides the first step in the formation of species. In ants, chromosome number varies tremendously from 2n = 2 to 2n = 120, and several studies have revealed considerable variation in karyotype within species. However, most previous studies were limited to the description of chromosome number and morphology, and more detailed karyomorphometric analyses may reveal additional, substantial variation.

Molecular phylogenetic reconstruction and localization of the (TTAGG)n telomeric repeats in the chromosomes of (Roger, 1863) suggests a lower ancestral karyotype for leafcutter ants (Hymenoptera).

Chromosome counts and karyotype characterization have proved to be important features of a genome. Chromosome changes during the diversification of ants might play an important role, given the diversity and success of Formicidae. Comparative karyotype analyses on ants have enriched and helped ant systematics.

Reassessing the Chromosome Number and Morphology of the Turtle Ant Cephalotes pusillus (Klug, 1824) Using Karyomorphometrical Analysis and Observations of New Nesting Behavior.

Here we use karyomorphometrical analysis to characterize and evaluate the karyotype of the turtle ant (Klug, 1824). This is the first representative of this diverse ant genus to be cytogenetically studied. They bear a diploid chromosome set of 44 chromosomes, which, according to the centromeric index, are metacentric, submetacentric, and subtelocentric.

Cytogenetic data on the agro-predatory ant Smith, 1947 and its host, (Mayr, 1884) (Hymenoptera, Formicidae).

We provide the first karyotype description of the agro-predatory ant species Smith, 1947 (Myrmicinae, Formicidae), and chromosome counts of its host (Mayr, 1884) (Myrmicinae, Formicidae) from geographically distinct populations. Colonies of both species were sampled from coastal areas of Ilhéus, Bahia, Brazil, and transferred to the laboratory. Metaphase spreads were prepared from the cerebral ganglia of defecated larvae.

Geographical Distribution Patterns and Niche Modeling of the Iconic Leafcutter Ant Acromyrmex striatus (Hymenoptera: Formicidae).

Ants are considered one of the most successful groups in the planet's evolutionary history. Among them highlights the fungus-farming ants of the genera Atta and Acromyrmex that occur throughout most of the Americas. Within the Acromyrmex genus, the species A.

Integrating Paleodistribution Models and Phylogeography in the Grass-Cutting Ant Acromyrmex striatus (Hymenoptera: Formicidae) in Southern Lowlands of South America.

Past climate changes often have influenced the present distribution and intraspecific genetic diversity of organisms. The objective of this study was to investigate the phylogeography and historical demography of populations of Acromyrmex striatus (Roger, 1863), a leaf-cutting ant species restricted to the open plains of South America. Additionally, we modeled the distribution of this species to predict its contemporary and historic habitat.

Phylogeography of the sand dune ant Mycetophylax simplex along the Brazilian Atlantic Forest coast: remarkably low mtDNA diversity and shallow population structure.

Background: During past glacial periods, many species of forest-dwelling animals experienced range contractions. In contrast, species living outside such moist habitats appear to have reacted to Quaternary changes in different ways. The Atlantic Forest represents an excellent opportunity to test phylogeographic hypotheses, because it has a wide range of vegetation types, including unforested habitats covered predominantly by herbaceous and shrubby plants, which are strongly influenced by the harsh environment with strong wind and high insolation.

Could pseudogenes be widespread in ants? Evidence of numts in the leafcutter ant Acromyrmex striatus (Roger, 1863) (Formicidae: Attini).

The incorporation of fragments of mitochondrial DNA (mtDNA) in the nuclear genome, known as numts (nuclear mitochondrial pseudogenes), undermines general assumptions concerning the use of mtDNA in phylogenetic and phylogeographic studies. Accidental amplifications of these nuclear copies instead of the mitochondrial target can lead to crucial misinterpretations, thus the correct identification of numts and their differentiation from true mitochondrial sequences are important in preventing this kind of error. Our goal was to describe the existence of cytochrome b (cytb) numts in the leafcutter ant Acromyrmex striatus (Roger, 1863).

The role of fusion in ant chromosome evolution: insights from cytogenetic analysis using a molecular phylogenetic approach in the genus mycetophylax.

Among insect taxa, ants exhibit one of the most variable chromosome numbers ranging from n = 1 to n = 60. This high karyotype diversity is suggested to be correlated to ants diversification. The karyotype evolution of ants is usually understood in terms of Robertsonian rearrangements towards an increase in chromosome numbers.