Evolution of sexual reproduction

Spolno razmnožavanje je način reprodukcije koje se uglavnom povezuje s eukariotima, a glavno obilježje mu je rekombinacija gena. U odnosu na nespolno razmnožavanje zahtijeva ulaganje veće količine energije pa je dugo nepoznanica bio razlog takve taktike razmnožavanja. Znanstvenici su došli mnogo bliže odgovoru na pitanje kada i zašto se spolno razmnožavanje razvilo. Smatra se da je takvo razmnožavanje poteklo od zajedničkog pretka svih eukariota starog oko 2 milijarde godina. Prema najistaknutijoj hipotezi spolno razmnožavanje ubrzava evoluciju. Miješanje vlastitog genskog materijala i kombiniranje njegovog djela s genskim materijalom drugog člana iste vrste omogućuje relativno brz nastanak novog genoma s moguće korisnim mutacijama. Pretpostavlja se da su eukarioti koji se razmnožavaju nespolno potekli od predaka sa spolnim razmnožavanjem, s obzirom da je i kod njih pronađena većina gena potrebnih za mejozu. Što su vrste s vremenom postajale odvedenije, napredovali su i njihovi mehanizmi povezani s razmnožavanjem. Spolni kromosomi su evoluirali zasebno više puta, a ustalili su se kod većine eukariota s odvojenim spolovima. Oblik prirodnog odabiranja kojeg proživljavaju sve vrste sa spolnim načinom razmnožavanja je spolna selekcija i o njoj ovisi hoće li jedinka imati potomstvo i koliko će ga biti. Spolna selekcija obuhvaća niz procesa i događaja koji se zbivaju između i unutar mužjaka i ženke iste vrste. Mehanizmi povezani sa spolom i spolnim načinom razmnožavanja su kodirani određenim genima i njihovo razumijevanje je važno za razumijevanje šire slike moćne prirodne sile, evolucije.Sexual reproduction is predominant type of reproduction which is mainly linked to eukaryotes and its main characteristic is recombination of genes. It requires significant costs relative to asexuality, so for a long-time reason for that kind of reproduction tactic was unknown. Scientists came much closer to answering questions like „When and why sexual reproduction has evolved? “. It is considered that sex first emerged in the common ancestor of all eukaryotes about 2 billion years ago. According to prominent hypothesis sex may speed up evolution. Shuffling their own DNA and combining some of it with the DNA of another member of the same species enables relatively quick production of new genome with possibly beneficial mutations. It is assumed that asexual eukaryotes evolved from sexual ancestors, considering their genome contains almost all the genes necessary for meiosis. As species evolved trough time, their reproduction mechanisms became more complex. Sex chromosomes have evolved independently many times in animals and plants, and held on to most eukaryotes with separate sexes. A form of natural selection that all sexual species go through is called sexual selection and it decides whether the individual will have offspring and how many there will be. Sexual selection includes many processes and events that happen in between and inside male and female of the same species. Mechanisms connected to sex and sexual form of reproduction, are coded by genes, and their understanding is important to recognize the bigger picture of powerful natural force, evolution

Morphological variability of daisy fleabane Erigeron annuus (L.) Pers. in Medvednica Mt. and city of Zagreb

Uz izravno uništavanje prirodnih staništa i promjene u načinu uporabe zemljišta, invazivne vrste su na globalnoj razini jedna od najvećih prijetnji bioraznolikosti. Jednogodišnja krasolika Erigeron annuus (L.) Pers. je korovna vrsta porijeklom iz Sjeverne Amerike koja u Hrvatskoj pridolazi sa svoje tri podvrste. Snažan je kompetitor iznimne otpornosti koji, formirajući guste i brojne sastojine, negativno utječe na samoniklu floru. Invazivnom potencijalu ove vrste potpomaže njena fenoplastičnost koja joj omogućava osvajanje širokog spektra staništa. U ovom radu istraživana je varijabilnost životnih značajki (visina stabljike, svježa i suha masa lista, duljina, širina i površina lista, specifična lisna površina, sadržaj suhe tvari lista) s 18 lokaliteta na području Medvednice i Zagreba. Ukupno je analizirano 435 listova. Izmjerene značajke analizirane su univarijatnim i multivarijatnim statističkim metodama. CR strategija biljaka određena je za jedinke sa svih lokaliteta, osim dva, za koje je ustanovljena C/CR strategija. Utvrđena je značajna morfološka varijabilnost istraživanih lokaliteta. Najveća varijabilnost zabilježena je za specifičnu lisnu površinu i visinu stabljike, te se analize ovih značajki preporučuju u budućim istraživanjima.Alongside to direct destruction of natural habitats and changes in land use, invasive species are considered one of the greatest threats to global biodiversity. Daisy fleabane Erigeron annuus (L.) Pers. is a weed native to North America, with three subspecies present in Croatia. As a vigorous competitor of extreme resistance, it overgrowths native species by forming dense and numerous stands. The invasive potential of this species is aided by its phenoplasticity, which enables it to conquer a wide range of habitats. This thesis investigates the variability of life traits (stem height, fresh and dry leaf mass, length, width and leaf area, specific leaf area, leaf dry matter content) among 18 locations throughout Zagreb and Medvednica Mt. Overall 435 leaves were measured and analysed using univariate and multivariate statistics. Except for two localities with C/CR plant strategy, plants from all other localities exhibited CR strategy. Significant differences between localities were found, with specific leaf area and plant height being the most diverse. Hence, latter characteristics should be used in subsequent research

Morphological variability of daisy fleabane Erigeron annuus (L.) Pers. in Medvednica Mt. and city of Zagreb

Uz izravno uništavanje prirodnih staništa i promjene u načinu uporabe zemljišta, invazivne vrste su na globalnoj razini jedna od najvećih prijetnji bioraznolikosti. Jednogodišnja krasolika Erigeron annuus (L.) Pers. je korovna vrsta porijeklom iz Sjeverne Amerike koja u Hrvatskoj pridolazi sa svoje tri podvrste. Snažan je kompetitor iznimne otpornosti koji, formirajući guste i brojne sastojine, negativno utječe na samoniklu floru. Invazivnom potencijalu ove vrste potpomaže njena fenoplastičnost koja joj omogućava osvajanje širokog spektra staništa. U ovom radu istraživana je varijabilnost životnih značajki (visina stabljike, svježa i suha masa lista, duljina, širina i površina lista, specifična lisna površina, sadržaj suhe tvari lista) s 18 lokaliteta na području Medvednice i Zagreba. Ukupno je analizirano 435 listova. Izmjerene značajke analizirane su univarijatnim i multivarijatnim statističkim metodama. CR strategija biljaka određena je za jedinke sa svih lokaliteta, osim dva, za koje je ustanovljena C/CR strategija. Utvrđena je značajna morfološka varijabilnost istraživanih lokaliteta. Najveća varijabilnost zabilježena je za specifičnu lisnu površinu i visinu stabljike, te se analize ovih značajki preporučuju u budućim istraživanjima.Alongside to direct destruction of natural habitats and changes in land use, invasive species are considered one of the greatest threats to global biodiversity. Daisy fleabane Erigeron annuus (L.) Pers. is a weed native to North America, with three subspecies present in Croatia. As a vigorous competitor of extreme resistance, it overgrowths native species by forming dense and numerous stands. The invasive potential of this species is aided by its phenoplasticity, which enables it to conquer a wide range of habitats. This thesis investigates the variability of life traits (stem height, fresh and dry leaf mass, length, width and leaf area, specific leaf area, leaf dry matter content) among 18 locations throughout Zagreb and Medvednica Mt. Overall 435 leaves were measured and analysed using univariate and multivariate statistics. Except for two localities with C/CR plant strategy, plants from all other localities exhibited CR strategy. Significant differences between localities were found, with specific leaf area and plant height being the most diverse. Hence, latter characteristics should be used in subsequent research

Consistent Grime’s CSR Strategy of Daisy Fleabane Erigeron annuus (L.) Pers. despite Its High Morphological Variability—A Case Study from Zagreb and Medvednica Mt., Croatia

Alongside the direct destruction of natural habitats and changes in land use, invasive species are considered one of the greatest threats to global biodiversity. Daisy fleabane Erigeron annuus (L.) Pers. is among the most widespread invasive plants in Croatia. Invasions of E. annuus may be aided by morphological variability, which this study investigates. The variability of life traits (stem height, fresh and dry leaf mass, length, width and leaf area, specific leaf area, and leaf dry matter content) was examined among 18 locations throughout Zagreb and Medvednica Mt. Overall, 87 plant specimens and 435 leaves were measured and analysed using univariate and multivariate statistics. Viable populations were recorded in diverse habitat types, mostly with marked human impact. We determined Grime’s CR plant life strategies for all, except for two localities with C/CR plant strategies. Two populations with a more pronounced competitive strategy had high leaf dry matter content, with smaller leaves and medium height stems. Significant differences between the localities were found, with the specific leaf area (SLA) and plant height being the most diverse. Despite its high morphological variability, daisy fleabane had a consistent CSR strategy, which likely enables its widespread invasions across variable habitats

Consistent Grime’s CSR Strategy of Daisy Fleabane <i>Erigeron annuus</i> (L.) Pers. despite Its High Morphological Variability—A Case Study from Zagreb and Medvednica Mt., Croatia

Alongside the direct destruction of natural habitats and changes in land use, invasive species are considered one of the greatest threats to global biodiversity. Daisy fleabane Erigeron annuus (L.) Pers. is among the most widespread invasive plants in Croatia. Invasions of E. annuus may be aided by morphological variability, which this study investigates. The variability of life traits (stem height, fresh and dry leaf mass, length, width and leaf area, specific leaf area, and leaf dry matter content) was examined among 18 locations throughout Zagreb and Medvednica Mt. Overall, 87 plant specimens and 435 leaves were measured and analysed using univariate and multivariate statistics. Viable populations were recorded in diverse habitat types, mostly with marked human impact. We determined Grime’s CR plant life strategies for all, except for two localities with C/CR plant strategies. Two populations with a more pronounced competitive strategy had high leaf dry matter content, with smaller leaves and medium height stems. Significant differences between the localities were found, with the specific leaf area (SLA) and plant height being the most diverse. Despite its high morphological variability, daisy fleabane had a consistent CSR strategy, which likely enables its widespread invasions across variable habitats